text:
Human intelligence, usually measured by IQ tests and related cognitive batteries, is **substantially heritable**, but not genetically fixed. The best summary is:

> In studied populations, genetic differences account for a meaningful share of differences in intelligence, with heritability typically rising from childhood into adulthood—roughly **40% in childhood** and often **60–80% in adulthood** in many twin-study estimates. Modern DNA-based estimates are lower, often around **20–30% for common measured genetic variants**, because they capture only part of the genetic contribution.

## What “heritable” means

Heritability is the proportion of variation in a trait within a particular population and environment that is statistically associated with genetic differences.

It does **not** mean:

- “X% of a person’s intelligence is genetic.”
- Intelligence is unchangeable.
- Environment is unimportant.
- Group differences are genetic.
- Heritability in one society applies to all societies.

A trait can be highly heritable and still be strongly affected by environment. For example, height is highly heritable, but nutrition and disease can greatly affect average height.

## Main evidence

### 1. Twin studies

Twin studies compare identical twins, who share essentially all their DNA, with fraternal twins, who share about half of their segregating DNA.

A consistent finding is:

- **Identical twins are more similar in IQ than fraternal twins.**
- Identical twins reared apart are still substantially similar.
- Similarity tends to increase with age.

Typical estimates:

| Age | Approximate heritability of IQ |
|---|---:|
| Early childhood | ~20–40% |
| Middle childhood/adolescence | ~40–60% |
| Adulthood | ~60–80% in many studies |

Shared family environment—things that make siblings similar, such as home resources or parenting style—often appears more important in childhood and less important in adulthood. Nonshared environment—experiences that make siblings different—also matters throughout life.

### 2. Adoption studies

Adoption studies find that adopted children’s cognitive scores are influenced by both biological and adoptive families.

Common pattern:

- In childhood, adopted children resemble both their adoptive and biological families to some degree.
- As they grow older, resemblance to biological relatives often increases.
- Resemblance to adoptive siblings often declines by adulthood.

This supports both genetic influence and environmental influence.

### 3. DNA/GWAS evidence

Genome-wide association studies show that intelligence and educational attainment are **highly polygenic**: influenced by thousands of genetic variants, each with tiny effects.

Important findings:

- No single “intelligence gene” exists.
- Polygenic scores can statistically predict a modest portion of variation in cognitive performance or educational outcomes.
- SNP heritability—heritability captured by common measured DNA variants—is usually lower than twin-study heritability, often around **20–30%** for cognitive ability, depending on sample and method.
- Prediction is imperfect and less reliable across ancestry groups or different social contexts.

GWAS evidence confirms that genetic variation contributes to cognitive differences, but it also shows the architecture is diffuse and probabilistic, not deterministic.

## Why does heritability increase with age?

One major explanation is **gene–environment correlation**. As people grow up, they increasingly select, shape, and create environments that match their dispositions and abilities.

For example, a child with stronger verbal ability may read more, seek intellectually demanding activities, receive more advanced instruction, and later choose education or careers that further amplify those differences.

So rising heritability does not mean the environment stops mattering. It may mean genetic differences partly influence exposure to environments.

## Environmental evidence is also strong

Environmental factors clearly affect cognitive development, including:

- Prenatal health and nutrition
- Lead exposure and other toxins
- Childhood illness
- School quality
- Poverty and stress
- Language exposure
- Sleep
- Malnutrition
- Access to books, safety, and stable caregiving

Large secular changes such as the **Flynn effect**—the substantial rise in IQ scores across generations in many countries during the 20th century—cannot be explained by genetic evolution over such a short time. They show that environmental and cultural changes can shift population averages substantially.

## Important limitations

### Heritability is population-specific

An estimate like “IQ is 60% heritable” applies to a particular population in a particular range of environments. If environments become more equal, heritability can rise because environmental variation shrinks. If environments become harsher or more unequal, environmental effects may dominate more.

### Heritability does not imply immutability

Highly heritable traits can be changed. Phenylketonuria, or PKU, is genetically caused, but its cognitive consequences can be largely prevented by diet. Height is highly heritable, yet average height has changed dramatically with improved nutrition and health.

### Heritability within groups does not explain between-group differences

Heritability estimates describe variation among individuals within a studied population. They do not by themselves explain differences between social, ethnic, national, or historical groups. Those differences can be strongly shaped by environment, history, policy, discrimination, health, schooling, and socioeconomic conditions.

### Twin studies have assumptions

Twin studies rely on assumptions such as equal environments for identical and fraternal twins. Researchers debate the exact magnitude of heritability, but the broad conclusion—both genes and environment matter substantially—is robust.

## Bottom line

The evidence shows that human intelligence is **moderately to highly heritable**, especially by adulthood, with many studies estimating adult heritability around **60% or more**. DNA-based methods confirm a genetic contribution but currently account for a smaller share, reflecting the highly polygenic nature of intelligence and methodological limits.

At the same time, intelligence is **not genetically predetermined**. Environment, education, health, family circumstances, social conditions, and individual experiences all play major roles. Heritability describes sources of variation in a given population; it does not tell us what any individual can achieve or what policies and environments can change.


prompt_id: sci-iq-heritability

provider: openai

text:
Human intelligence (often measured as general cognitive ability or **IQ/g**) is **substantially heritable**, but heritability is not destiny and does not mean intelligence is fixed or unaffected by environment.

## Short answer

- In modern developed populations, **heritability of intelligence is usually estimated around 50% on average**, but it varies by age and context.
- It tends to **increase with age**:
  - Childhood: roughly **20–40%**
  - Adolescence: roughly **40–60%**
  - Adulthood: often **60–80%**
- Environment still matters a lot, especially early in life and in disadvantaged conditions.
- Heritability describes **differences among people within a population**, not how much of an individual’s intelligence is “genetic.”
- Evidence comes from **twin studies, adoption studies, family studies, and DNA-based genome-wide studies**.

## What “heritability” means

Heritability is the proportion of variation in a trait within a particular population and environment that is statistically associated with genetic differences.

So if IQ heritability is estimated at 60%, that does **not** mean:
- 60% of your intelligence is genetic and 40% is environmental.
- intelligence cannot change.
- environment is unimportant.

It means that, in that population at that time, about 60% of the **differences between individuals** in measured cognitive ability are associated with genetic differences.

## Evidence from twin studies

Twin studies compare identical twins, who share nearly all their DNA, with fraternal twins, who share about half of their segregating DNA.

The basic finding is robust:

- **Identical twins are more similar in IQ than fraternal twins.**
- Identical twins raised apart are still often substantially similar.
- Fraternal twins and ordinary siblings are less similar.

This pattern strongly suggests genetic influence.

Typical correlations reported in the literature are approximately:

- Identical twins raised together: **~0.75–0.85**
- Fraternal twins raised together: **~0.40–0.60**
- Identical twins raised apart: **~0.65–0.75**
- Adoptive siblings raised together: much lower by adulthood, often near **0–0.20**

These numbers vary by study, age, and population, but the overall pattern is consistent.

## Evidence from adoption studies

Adoption studies help separate genetic relatedness from shared family environment.

Common findings:

- In childhood, adopted children’s IQ scores are influenced by the adoptive home environment.
- As children grow older, their IQ tends to become more similar to their biological relatives and less similar to unrelated adoptive siblings.
- The effect of the shared family environment often appears to decline by adulthood in many studies.

This does **not** mean parenting or schooling do not matter. Rather, it suggests that within the range of environments studied, lasting differences in adult IQ are more strongly associated with genetic differences and non-shared environmental experiences than with shared family background.

## DNA-based evidence

Modern genome-wide association studies, or GWAS, examine measured DNA directly.

They show that intelligence is **highly polygenic**: influenced by thousands of genetic variants, each with tiny effects.

Key findings:

- Common genetic variants captured by SNP arrays explain a meaningful portion of IQ variation.
- SNP-based heritability estimates are often around **20–30%** for cognitive ability, lower than twin-study estimates because they capture only part of genetic variation.
- Polygenic scores can predict some differences in educational attainment and cognitive performance, but their predictive power is still limited at the individual level.

For example, a polygenic score may tell us something statistically about group-level tendencies, but it is far from being able to accurately predict an individual person’s intelligence.

## Why does heritability increase with age?

A striking finding is that IQ heritability tends to rise from childhood to adulthood.

Possible reasons include:

1. **Gene–environment correlation**
   As people grow older, they increasingly select, shape, and create environments that fit their genetic tendencies. For example, a child with a tendency toward verbal ability may read more, seek intellectually stimulating peers, and choose challenging courses.

2. **Reduced influence of shared family environment**
   Family-wide influences such as household income, parenting style, and neighborhood may be stronger in childhood but often become less predictive of adult IQ differences.

3. **Accumulation of small choices and experiences**
   Genetically influenced preferences can compound over time.

## Environment still matters

High heritability does not imply immutability. Traits with high heritability can be strongly affected by environment. Height is a classic example: it is highly heritable, yet nutrition and disease exposure can greatly affect average height.

For intelligence, environmental influences include:

- prenatal health
- nutrition
- exposure to toxins such as lead
- childhood illness
- schooling quality
- stress and trauma
- sleep
- socioeconomic deprivation
- cognitive stimulation
- access to books, language, and educational opportunities

Severe deprivation can have large negative effects. Conversely, improvements in nutrition, schooling, health care, and environmental safety can raise average cognitive performance.

The **Flynn effect**, the large rise in IQ scores across much of the 20th century, is strong evidence that environmental changes can substantially affect measured intelligence at the population level.

## Heritability varies by social context

Heritability is not a universal constant.

In affluent, stable environments where children have broadly similar access to nutrition, education, and safety, genetic differences may explain more of the remaining variation.

In deprived or unequal environments, environmental differences may explain more variation. Some studies, especially in the United States, have found that IQ heritability is lower among children from lower socioeconomic backgrounds, although findings are not perfectly consistent across countries.

## What the evidence does not show

The evidence does **not** show that:

- intelligence is fixed at birth
- education is pointless
- individual potential can be read from genes
- IQ tests measure every important form of intelligence
- group differences between populations are genetic in origin

Heritability within a population cannot by itself explain differences between populations. For example, height is highly heritable within countries, but average height differences between countries can be largely environmental.

## Bottom line

The best evidence indicates that human intelligence is **moderately to highly heritable**, especially by adulthood. A reasonable summary is:

> Genetic differences account for roughly half or more of the variation in measured intelligence in many studied populations, with heritability increasing from childhood into adulthood.

But intelligence is also shaped by environment, development, education, health, and opportunity. Genes influence cognitive ability through many small effects and through interactions with environments; they do not determine a person’s intellectual fate.

finish_reason: stop


text:
Human intelligence (usually measured by IQ or related cognitive test scores) is **substantially heritable**, but heritability is **not 100%**, varies by context, and does **not** mean intelligence is fixed or unaffected by environment.

## Short answer

In modern behavioral genetics, the heritability of IQ is typically estimated at roughly:

- **Childhood:** ~20–50%
- **Adolescence:** ~40–60%
- **Adulthood:** ~50–80%

A common summary is that **about half or more of the variation in adult IQ within a given population is associated with genetic differences**, with the rest due to environmental influences, measurement error, developmental factors, and gene–environment interplay.

## What “heritability” means

Heritability is often misunderstood. It means:

> The proportion of variation in a trait within a particular population, at a particular time, attributable to genetic differences among individuals.

It does **not** mean:

- “X% of a person’s intelligence is genetic”
- Intelligence is unchangeable
- Environment does not matter
- Genetic differences explain differences between social groups or countries
- A high heritability rules out large environmental effects

For example, height is highly heritable, but nutrition can still strongly affect height.

## Main evidence

### 1. Twin studies

Twin studies compare identical twins, who share nearly all their DNA, with fraternal twins, who share about half of their segregating genetic variation.

Findings consistently show:

- Identical twins are more similar in IQ than fraternal twins.
- Identical twins raised apart are still substantially similar.
- Genetic influence tends to increase from childhood into adulthood.

Typical adult estimates from twin studies are often around **60–80% heritability**, though estimates vary by sample and method.

### 2. Adoption studies

Adoption studies compare children’s IQ resemblance to biological versus adoptive relatives.

Common findings:

- In childhood, adopted children’s IQs are influenced by the adoptive family environment.
- As children age, their IQ scores tend to become more similar to their biological parents’ IQs and less similar to adoptive parents’.
- Shared family environment appears more important in childhood than adulthood.

This supports both genetic influence and environmental influence.

### 3. Genome-wide association studies, or GWAS

Modern genetic studies examine millions of DNA variants across very large samples.

They show that cognitive ability is **highly polygenic**: influenced by thousands of genetic variants, each with very small effects.

Important points:

- No single “intelligence gene” exists.
- Polygenic scores can predict some variation in educational attainment and cognitive performance, but far from all of it.
- Current polygenic scores explain a modest fraction of cognitive variation, much less than twin-study heritability estimates.
- Their predictive accuracy depends strongly on ancestry, social context, and the datasets used.

GWAS evidence supports a real genetic contribution, but also shows that intelligence is genetically complex and deeply entangled with environment.

## Why heritability changes with age

Heritability of IQ tends to increase from childhood to adulthood. Possible reasons include:

- As people age, they increasingly select environments that match their abilities and interests.
- Genetic tendencies may influence educational choices, hobbies, peer groups, and intellectual practice.
- Adults often have more freedom than children to shape their environments.

This is called **gene–environment correlation**.

## Environmental influences still matter

Even when heritability is high, environment can have major effects. Relevant factors include:

- Prenatal health
- Nutrition
- Exposure to toxins such as lead
- Childhood illness
- Stress and trauma
- Quality of schooling
- Family resources
- Sleep
- Social stability
- Access to books, language, and cognitive stimulation

The **Flynn effect**—the large rise in average IQ scores across many countries during the 20th century—is strong evidence that environmental changes can shift population-level cognitive performance substantially.

## Socioeconomic context matters

Some studies suggest that heritability of IQ may be lower in disadvantaged environments and higher in more advantaged ones, especially in childhood. The idea is that deprivation can suppress the expression of genetic potential.

However, this pattern is not identical across countries or studies. In societies with stronger social supports, the relationship between socioeconomic status and heritability may differ.

## What the evidence does not show

The evidence does **not** justify simple genetic determinism.

It does not show that:

- IQ is fixed at birth.
- Education is ineffective.
- Social policy cannot affect cognitive outcomes.
- Group differences are genetically caused.
- Individual potential can be accurately read from DNA.

Heritability estimates describe variation **within studied populations**, not the causes of differences **between populations**, especially when environments differ.

## Bottom line

Human intelligence is **moderately to highly heritable**, especially in adulthood, with many studies converging on estimates around **50–80%** for adult IQ variation in developed populations. The evidence comes from twin, adoption, family, and molecular genetic studies.

But intelligence is also shaped by environment, development, education, health, and social conditions. Heritability is a population statistic, not a measure of destiny.


text:
Human intelligence (often measured with IQ tests or broader cognitive batteries) is **substantially heritable**, but **not genetically determined**. The best evidence suggests that, in modern industrialized populations, genetic differences explain a large share of individual differences in cognitive ability—especially in adulthood—while environment also has important effects.

## Short answer

- **Childhood IQ heritability:** roughly **30–50%**
- **Adolescent/adult IQ heritability:** roughly **50–80%**
- A common summary estimate for adult general cognitive ability is around **60–70% heritable**
- The remaining variation reflects **nonshared environment, measurement error, developmental randomness**, and in childhood more **shared family environment**

These numbers are **population-specific**: heritability can change across societies, age, socioeconomic conditions, schooling quality, nutrition, and other environmental contexts.

## What “heritability” means

Heritability is the proportion of variation in a trait **within a given population at a given time** that is statistically associated with genetic differences.

It does **not** mean:

- “70% of a person’s intelligence is genetic”
- “IQ cannot be changed”
- “environment does not matter”
- “group differences are genetic”
- “genes act independently of environment”

For example, height is highly heritable, but average height has risen dramatically in many countries because of nutrition and health improvements. The same logic applies to cognitive ability.

## Main lines of evidence

### 1. Twin studies

Twin studies compare identical twins, who share nearly all their DNA, with fraternal twins, who share about half of their segregating DNA.

Findings are consistent:

- Identical twins are more similar in IQ than fraternal twins.
- Identical twins reared apart are still substantially similar.
- Heritability estimates increase with age.

Meta-analyses generally find IQ heritability around:

- **~0.4 in childhood**
- **~0.5–0.6 in adolescence**
- **~0.7 or higher in adulthood**

Shared family environment tends to matter more in childhood and less in adulthood.

### 2. Adoption studies

Adoption studies compare adopted children with their biological and adoptive relatives.

Typical findings:

- In childhood, adopted children’s IQ is influenced by the adoptive home.
- As children grow older, their IQ tends to become more similar to that of their biological relatives.
- Resemblance to adoptive siblings often declines by adulthood.

This supports both genetic influence and environmental influence, with genetic influence becoming more apparent over development.

### 3. Molecular genetic studies

Genome-wide association studies, or GWAS, examine measured DNA variants across very large samples.

They show that intelligence is **highly polygenic**: influenced by thousands of genetic variants, each with very small effect.

Key findings:

- Common genetic variants captured by SNP arrays explain roughly **20–30%** of variation in cognitive ability in many studies.
- Polygenic scores for educational attainment and cognitive performance can predict some differences in educational outcomes and test performance, especially in European-ancestry samples.
- Current polygenic scores explain far less than twin-study heritability estimates, partly because many causal variants are not well captured and effects are tiny.

This confirms that genetic influence is real, but also shows that no small set of “intelligence genes” exists.

## Why heritability increases with age

It may seem surprising that IQ becomes more heritable as people age, but several mechanisms can explain this:

1. **Gene–environment correlation**
   People increasingly select and shape environments that fit their dispositions. A child with stronger verbal ability may read more, seek advanced classes, and get more intellectual stimulation.

2. **Greater autonomy**
   Adults choose occupations, hobbies, peers, and learning environments more than children do.

3. **Amplification over time**
   Small early differences can compound through education, motivation, feedback, and opportunity.

So higher adult heritability does not mean the environment stops mattering. It means genetic differences become more correlated with the environments people experience.

## Environmental effects are real

Many environmental factors affect cognitive development, including:

- prenatal health
- nutrition
- infectious disease burden
- lead and other toxins
- schooling quality and duration
- poverty and stress
- sleep
- family instability
- severe deprivation or neglect
- access to books, language, and enrichment
- cultural and test familiarity

Evidence for environmental influence includes:

- the **Flynn effect**, where average IQ scores rose substantially across generations in many countries
- cognitive harm from lead exposure, iodine deficiency, severe malnutrition, and institutional deprivation
- gains from schooling and early-childhood interventions, though effect sizes and durability vary
- adoption from deprived into enriched environments often improving cognitive outcomes

## Important caveats

### Heritability is not immutability

A trait can be highly heritable and still modifiable. Phenylketonuria is genetically caused but treatable by diet. Height is highly heritable but strongly affected by nutrition and disease.

### Heritability is population-specific

If environments become more equal, genetic differences may explain more of the remaining variation. If environments are highly unequal, environmental differences may explain more.

### Heritability within groups does not explain between-group differences

A high heritability estimate within a population says little about why two groups differ on average. Group differences can be caused by environmental factors even when within-group heritability is high.

### IQ is not all of intelligence

IQ tests measure important cognitive abilities, especially general reasoning, working memory, verbal ability, processing speed, and problem-solving. They predict academic and occupational outcomes reasonably well. But human intelligence is broader than IQ and includes practical knowledge, creativity, social cognition, motivation, personality, and domain-specific skill.

## Bottom line

The evidence from twin, adoption, family, and molecular genetic studies shows that **human intelligence is moderately to highly heritable**, especially in adulthood. A reasonable estimate is that genetic differences account for roughly **half or more of individual differences in adult cognitive ability** in many contemporary populations.

But intelligence is also shaped by environment, development, culture, education, health, and opportunity. Heritability describes variation in a population; it does not make intelligence fixed, purely genetic, or immune to social and educational intervention.


text:
Human intelligence, usually measured by IQ tests or a broader “general cognitive ability” factor, is **substantially heritable**, but not genetically fixed. The best summary is:

> **In modern industrialized populations, genetic differences account for roughly 40–80% of individual differences in measured intelligence, with heritability generally increasing from childhood into adulthood.**

That does **not** mean intelligence is “80% genetic” for an individual, nor that environment is unimportant. Heritability is a population statistic: it estimates how much of the variation among people in a given environment is associated with genetic variation.

## What the evidence shows

### 1. Twin and family studies

Twin studies are a major source of evidence. Identical twins share nearly all their DNA; fraternal twins share about half, on average.

Typical findings:

- **Identical twins raised together** have very similar IQ scores.
- **Identical twins raised apart** are also strongly similar, though usually less so.
- **Fraternal twins and ordinary siblings** are less similar than identical twins.
- **Adopted children** resemble their biological parents increasingly with age and often resemble adoptive parents less in adulthood.

These patterns suggest a strong genetic contribution.

Approximate heritability estimates by age:

| Age | Approximate heritability of IQ/general cognitive ability |
|---|---:|
| Early childhood | ~20–40% |
| Middle childhood/adolescence | ~40–60% |
| Adulthood | ~50–80% |

The increase with age may seem surprising, but it likely reflects people increasingly selecting, shaping, and responding to environments that fit their genetic tendencies — for example, reading more, choosing certain friends, pursuing certain subjects, or entering cognitively demanding work.

### 2. Adoption studies

Adoption studies support both genetic and environmental effects.

Findings generally show:

- Adopted children’s IQs are influenced by the adoptive home, especially in childhood.
- By adulthood, IQ tends to correlate more strongly with biological relatives than with adoptive relatives.
- Improved environments, such as moving from deprivation to stable homes, can raise cognitive outcomes substantially.

So genes matter, but environmental quality also clearly matters.

### 3. Genome-wide studies

Modern DNA studies confirm that intelligence is **highly polygenic**: influenced by thousands of genetic variants, each with tiny effects.

Genome-wide association studies find that common genetic variants explain a meaningful but incomplete share of variation:

- “SNP heritability” for cognitive ability is often estimated around **20–30%**, depending on the sample and measurement.
- Polygenic scores can predict some variance in cognitive outcomes, but they are far from deterministic.
- Prediction is currently much better in people of European ancestry because most studies have used European-ancestry samples, making portability across ancestries limited.

DNA evidence therefore supports the basic conclusion from twin/adoption studies: intelligence is heritable, but influenced by many genes and by environment.

## Important caveats

### Heritability is not immutability

A trait can be highly heritable and still change due to environment. Height is highly heritable, yet average height increased in many countries due to nutrition and health improvements.

Similarly, IQ scores rose dramatically across the 20th century in many places — the **Flynn effect** — showing that environmental changes can shift cognitive test performance substantially.

### Heritability depends on the population and environment

If environments are very unequal — for example, large differences in nutrition, schooling, disease burden, or stress — environmental effects can explain more variation.

If environments are relatively equal, genetic differences may explain a larger share of remaining variation.

So a heritability estimate from one society at one time does not automatically apply everywhere.

### Heritability does not explain group differences

Heritability within a population does not tell us why two groups differ on average. For example, the fact that height is heritable within countries does not mean average height differences between countries are genetic; nutrition and health can drive group differences.

The same logic applies to intelligence.

### Intelligence is not a single simple trait

IQ tests measure important cognitive abilities and predict outcomes such as educational achievement, job performance, and health to some degree. But they do not capture every valuable mental trait — creativity, wisdom, motivation, emotional regulation, practical knowledge, and personality also matter.

## Bottom line

The evidence from twin, adoption, family, and DNA studies shows that **human intelligence is moderately to highly heritable**, especially in adulthood. A reasonable summary is:

- **Childhood:** genetic influence is moderate.
- **Adulthood:** genetic influence is substantial, often around **50–70%**, sometimes estimated higher.
- **Environment remains important**, especially early-life conditions, education, nutrition, health, stress, and opportunity.
- Intelligence is **polygenic and probabilistic**, not controlled by a few “intelligence genes.”
- High heritability does **not** mean fixed, inevitable, or unaffected by social policy or personal experience.


text:
Human intelligence, as measured by IQ tests or broader cognitive test batteries, is **substantially heritable**, but not genetically fixed. The best-supported conclusion is:

> In modern, relatively well-nourished populations, genetic differences explain a large share of individual differences in measured intelligence, especially in adulthood—often roughly **50–80%**—while environments also matter, especially in childhood and for population-level changes.

## What “heritability” means

Heritability is the proportion of variation in a trait **within a given population and environment** that is statistically associated with genetic differences.

It does **not** mean:

- “X% of a person’s intelligence is genetic.”
- Intelligence is unchangeable.
- Environmental interventions cannot matter.
- Differences between social groups are genetic.
- The same estimate applies in every society or historical period.

A trait can be highly heritable and still strongly affected by environment. For example, height is highly heritable in well-fed populations, but average height can rise dramatically with better nutrition and health.

## Approximate heritability estimates by age

A common pattern in the literature is that heritability of cognitive ability tends to **increase with age**:

| Age range | Approximate heritability of IQ/general cognitive ability |
|---|---:|
| Early childhood | ~20–40% |
| Middle childhood/adolescence | ~40–60% |
| Adulthood | ~50–80% |

A reasonable summary is that adult intelligence in contemporary developed countries is often estimated to be around **60% heritable**, with some studies higher or lower.

The increase with age likely reflects several processes, including people increasingly selecting, shaping, and evoking environments correlated with their genetic tendencies—what behavioral geneticists call **gene–environment correlation**.

## Evidence from twin studies

Twin studies compare identical twins, who share nearly all their DNA, with fraternal twins, who share about half of their segregating DNA.

The consistent finding is:

- Identical twins are more similar in IQ than fraternal twins.
- Identical twins reared apart are still substantially similar.
- Fraternal twins and ordinary siblings are less similar.

This supports a genetic contribution to intelligence.

However, twin studies rely on assumptions, such as the “equal environments” assumption: that identical and fraternal twins experience similarly correlated environments relevant to the trait. Researchers debate the details, but the broad finding of genetic influence is robust across many designs.

## Evidence from adoption studies

Adoption studies provide another line of evidence.

Findings often show that:

- In early childhood, adopted children’s IQs can resemble those of their adoptive families.
- As children age, their IQs tend to correlate more strongly with their biological relatives than with adoptive relatives.
- Shared family environment appears to matter more in childhood and less in adulthood for IQ differences within many studied populations.

This does not mean parenting or schooling are irrelevant. It means that, among the families studied, differences between family environments often explain less of the adult variation in IQ than genetic differences do.

## Evidence from DNA/GWAS studies

Modern genome-wide association studies find that intelligence and educational attainment are **highly polygenic**: influenced by thousands of genetic variants, each with tiny effects.

Key points:

- No single “intelligence gene” exists.
- Common genetic variants together explain a meaningful but incomplete share of variation.
- SNP-based heritability estimates for cognitive performance are generally lower than twin-study estimates, often roughly in the **20–40%** range depending on sample, phenotype, and method.
- Polygenic scores can predict some variation in educational and cognitive outcomes, but they are far from deterministic and are much less informative for individuals than for large-group statistical research.

The gap between twin-study heritability and SNP-based heritability is sometimes called “missing heritability.” It may reflect rare variants, structural variants, non-additive genetic effects, measurement issues, and limitations of current genomic data.

## Environmental evidence is also strong

Even if intelligence is substantially heritable, environment clearly matters.

Evidence includes:

- **Flynn effect:** Average IQ scores rose markedly across much of the 20th century, too quickly to be genetic. This points to environmental causes such as schooling, nutrition, health, smaller families, cognitive complexity, and test familiarity.
- **Education effects:** More schooling tends to improve performance on cognitive tests.
- **Nutrition and health:** Iodine deficiency, lead exposure, prenatal alcohol exposure, malnutrition, infectious disease burden, sleep deprivation, and chronic stress can affect cognitive development.
- **Early deprivation:** Severe neglect or institutional deprivation can cause large cognitive deficits, some of which may improve after environmental improvement.
- **Socioeconomic context:** In some studies, heritability of IQ is lower in disadvantaged environments, especially in childhood, suggesting that deprivation can suppress genetic potential. This finding is stronger in some U.S. samples than in many European samples, so it is not universal.

## Shared vs non-shared environment

Behavioral genetics often divides environmental influences into:

1. **Shared environment:** Factors making siblings more similar, such as family socioeconomic status, neighborhood, parenting style, and household resources.
2. **Non-shared environment:** Factors making siblings different, such as different peers, teachers, illnesses, accidents, differential treatment, and random developmental variation.

For IQ:

- Shared environment tends to have a larger effect in childhood.
- Its estimated effect often declines by adulthood.
- Non-shared environment and measurement error remain important.

## Important cautions

Heritability estimates are easily misunderstood.

### 1. Heritability is population-specific

A heritability estimate from affluent, industrialized societies does not necessarily apply to populations facing famine, disease, poor schooling, or severe deprivation.

If everyone has similar access to nutrition and education, genetic variation may explain more of the remaining differences. If environments differ greatly, environmental variation may explain more.

### 2. Heritability does not imply immutability

High heritability does not mean a trait cannot be changed. Poor vision is heritable, but glasses work. Phenylketonuria is genetic, but diet can prevent severe cognitive impairment.

### 3. Heritability within groups does not explain differences between groups

A high heritability estimate within a population says little about why two populations differ in average IQ scores. Between-group differences can be environmental even when within-group heritability is high.

### 4. IQ is not the whole of intelligence

IQ tests measure important cognitive abilities, especially general reasoning, working memory, processing speed, verbal ability, and spatial ability. They predict many life outcomes, but they do not capture every valuable mental trait, such as wisdom, creativity, motivation, emotional regulation, or practical expertise.

## Bottom line

The evidence from twin, adoption, family, and molecular genetic studies shows that **human intelligence is substantially heritable**, especially in adulthood. In many modern populations, adult IQ heritability is often estimated around **50–80%**, with childhood estimates lower.

But intelligence is also meaningfully shaped by environment. Nutrition, health, schooling, toxins, stress, family resources, culture, and historical change all matter. The best view is not “genes versus environment,” but **genes and environments interacting across development**.


text:
Human intelligence is **substantially heritable**, but heritability is often misunderstood. The best evidence suggests that genetic differences explain a meaningful fraction of variation in cognitive ability **within a given population**, while environment also matters—especially in childhood.

## Short answer

Across modern behavioral-genetic studies:

- **Childhood intelligence:** roughly **30–50% heritable**
- **Adolescent intelligence:** roughly **40–60% heritable**
- **Adult intelligence:** often **50–80% heritable**
- **Shared family environment:** important in childhood, usually smaller in adulthood
- **Non-shared environment, measurement error, development, education, health, and chance:** still account for a substantial fraction

A common summary is: **intelligence is moderately heritable in childhood and highly heritable in adulthood**, but it is not genetically fixed.

## What “heritability” means

Heritability is the proportion of variation in a trait, in a particular population and environment, that is statistically associated with genetic differences.

It does **not** mean:

- “X% of a person’s intelligence is genetic”
- intelligence cannot be changed
- environment is unimportant
- genetic differences explain differences between social groups or countries

For example, if adult IQ has a heritability of 60%, that means about 60% of the observed variation in IQ in that studied population is associated with genetic variation under those environmental conditions.

## Main lines of evidence

### 1. Twin studies

Twin studies compare identical twins, who share nearly all their DNA, with fraternal twins, who share about half of their segregating DNA.

A typical finding:

- Identical twins are more similar in IQ than fraternal twins.
- Identical twins raised apart are still quite similar.
- Fraternal twins and siblings are less similar.

This pattern strongly suggests genetic influence.

Classic and modern twin studies generally find:

- Heritability of IQ rises from childhood into adulthood.
- Shared home environment has stronger effects in childhood.
- By adulthood, genetic differences account for more of the stable variation.

### 2. Adoption studies

Adoption studies show that adopted children often resemble their adoptive families in childhood, but as they age, their cognitive scores tend to become more similar to their biological relatives.

This suggests:

- Family environment matters, especially early.
- Genetic influences become more apparent as individuals grow older and select, shape, or evoke environments compatible with their dispositions.

### 3. Genome-wide association studies

Modern DNA studies confirm that intelligence is **highly polygenic**: influenced by thousands of genetic variants, each with very small effects.

GWAS findings show:

- No single “intelligence gene” exists.
- Polygenic scores can predict some variation in educational attainment and cognitive performance.
- SNP-based heritability estimates are lower than twin-study estimates, often around **20–30%** for measured common variants, because they miss rare variants, structural variants, gene–gene interactions, and other sources of genetic similarity.

The molecular evidence supports the conclusion that genetic differences contribute to cognitive differences, but it also shows that the genetic architecture is complex and diffuse.

## Why heritability increases with age

One of the most replicated findings is that the heritability of intelligence tends to rise from childhood to adulthood. This may happen because:

- Adults have more freedom to choose environments that match their abilities and interests.
- Small genetic tendencies can compound over time.
- Education, hobbies, peer groups, and occupations become partly self-selected.
- Shared family effects weaken as siblings leave the home.

This does not mean genes “turn on” intelligence in adulthood. Rather, genetic differences may increasingly influence the environments people experience.

## Environmental influences still matter

Even if intelligence is substantially heritable, environment remains important. Factors associated with cognitive development include:

- Nutrition
- Prenatal health
- Childhood disease burden
- Lead and toxin exposure
- Sleep
- School quality
- Literacy and intellectual stimulation
- Stress and trauma
- Family resources
- Social stability
- Access to healthcare

Large environmental changes can raise or lower population-level cognitive performance. The **Flynn effect**, the large rise in IQ scores over the 20th century in many countries, is strong evidence that environments can affect measured intelligence substantially.

## Important caveats

### Heritability is population-specific

Heritability depends on the range of genes and environments in the population studied. In a society where environments are more equal, genetic differences may explain more of the remaining variation. In a society with severe deprivation or unequal schooling, environmental differences may explain more.

### High heritability does not mean immutability

Height is highly heritable, but nutrition can strongly affect height. Similarly, intelligence can be heritable and still influenced by education, health, poverty, toxins, and other environmental factors.

### Heritability within groups does not explain between-group differences

A high heritability estimate within a population does not imply that differences between populations, ethnic groups, socioeconomic groups, or countries are genetic. Between-group differences can be heavily environmental even when within-group differences are heritable.

### Intelligence is not a single simple trait

IQ tests measure a broad cognitive factor often called **general intelligence**, or **g**, along with more specific abilities such as verbal reasoning, spatial ability, working memory, and processing speed. These abilities are correlated, but not identical.

## Bottom line

The evidence from twin, adoption, family, and DNA studies shows that **human intelligence is substantially influenced by genetic differences**, especially in adulthood. A reasonable broad estimate is that intelligence is about **40–50% heritable in childhood** and **60% or more heritable in adulthood**, depending on the population and method.

But intelligence is also meaningfully shaped by environment, development, education, health, and social conditions. Heritability is not destiny; it is a statistical description of variation, not a limit on human potential.


text:
Human intelligence (often measured with IQ or broader cognitive ability tests) is **substantially heritable within studied populations**, but it is also strongly influenced by environment, development, education, health, and chance. A good shorthand is:

- **Childhood:** heritability often estimated around **20–50%**
- **Adolescence/adulthood:** often around **50–80%**
- **Old age:** estimates vary; cognitive aging and health factors add complexity

These numbers refer to **variation among people in a particular population at a particular time**, not to how “fixed” intelligence is in an individual.

## What “heritability” means

Heritability is the proportion of observed differences in a trait within a population that can be statistically associated with genetic differences.

So if IQ heritability is estimated at 60%, that does **not** mean:

- 60% of a person’s intelligence is genetic
- intelligence cannot be changed
- environmental interventions are unimportant
- group differences are genetic

It means that, in the studied population and environment, genetic differences are associated with about 60% of the variation in measured cognitive ability.

A trait can be highly heritable and still be environmentally changeable. For example, height is highly heritable, but nutrition and disease burden can greatly affect average height.

## Main lines of evidence

### 1. Twin studies

Twin studies compare identical twins, who share nearly all their DNA, with fraternal twins, who share about half their segregating DNA.

Findings:

- Identical twins tend to be more similar in IQ than fraternal twins.
- Identical twins raised apart are still substantially similar.
- The genetic contribution tends to increase from childhood into adulthood.

Typical adult heritability estimates from twin studies are often around **50–80%**.

Limitations:

- Twin studies rely on assumptions, such as equal similarity of environments for identical and fraternal twins.
- They are strongest for estimating variation within the populations studied, not universal constants.
- They can sometimes overestimate or misattribute genetic/environmental effects if assumptions are violated.

### 2. Adoption studies

Adoption studies compare children with biological and adoptive relatives.

Findings:

- In childhood, adopted children’s IQs often resemble both adoptive family environment and biological relatives.
- As children age, resemblance to biological relatives tends to increase.
- Shared family environment appears more important in childhood and often less predictive of adult IQ.

This supports the idea that both genes and environment matter, with genetic influence becoming more visible as people grow older and select or shape environments compatible with their dispositions.

### 3. Genome-wide association studies, or GWAS

Modern genetic studies examine millions of DNA variants across very large samples.

Findings:

- Intelligence and educational attainment are **highly polygenic**: influenced by thousands of genetic variants, each with tiny effects.
- Common measured SNPs explain a meaningful but incomplete portion of cognitive differences.
- “SNP heritability” estimates for cognitive ability are typically lower than twin-study estimates, often around **20–30%**, depending on the sample and measure.
- Polygenic scores can predict some differences in cognitive performance and educational outcomes, but their predictive power is still limited.

Important caveats:

- Polygenic scores are probabilistic, not deterministic.
- They work best in populations similar to the discovery samples, which have historically been heavily European-ancestry.
- Genetic associations can partly reflect indirect environmental pathways, such as parental education, neighborhood, and schooling.

## Why heritability increases with age

A striking finding is that heritability of intelligence often rises from childhood to adulthood.

Possible explanations include:

1. **Gene–environment correlation:** people increasingly choose environments that fit their genetic tendencies, such as reading, academic tracks, hobbies, or occupations.
2. **Reduced shared family influence:** the common household environment matters more in childhood and less as people leave home.
3. **Amplification over time:** small early differences can compound through educational and social feedback.

This does not mean early environment is unimportant. Early nutrition, safety, schooling, parental interaction, toxins, stress, and health can have lasting effects.

## Environmental evidence is also strong

Evidence for environmental influence includes:

- The **Flynn effect**: large increases in average IQ scores across many countries during the 20th century, too rapid to be genetic.
- Effects of schooling: more education is associated with higher cognitive test performance.
- Impacts of deprivation: severe neglect, malnutrition, lead exposure, disease burden, and chronic stress can reduce cognitive development.
- Intervention evidence: early childhood programs can improve outcomes, though effects on IQ itself may fade or vary while effects on education, employment, and health can persist.
- Socioeconomic context: heritability estimates can differ by environment; in more deprived settings, environmental constraints may suppress genetic potential.

## What the evidence shows overall

The broad consensus is:

1. **Human intelligence is heritable.** Genetic differences account for a substantial portion of individual variation in cognitive ability within many studied populations.

2. **It is not controlled by a single gene or small set of genes.** It is massively polygenic, with thousands of variants contributing tiny effects.

3. **Environment matters greatly.** Nutrition, schooling, health, family environment, social conditions, toxins, and broader culture all influence cognitive development and measured performance.

4. **Heritability is population-specific.** A high heritability estimate within one society does not imply that differences between societies, social classes, historical periods, or other groups are genetic.

5. **Heritability does not imply immutability.** Traits with high heritability can still be changed by environmental intervention.

6. **Current genetic prediction is limited.** Polygenic scores can predict some variation, especially in large research samples, but they are far from determining an individual’s intelligence.

In short: **intelligence is moderately to highly heritable, especially in adulthood, but it is also deeply shaped by environment. The best evidence supports a complex developmental picture in which many genetic influences interact with many environmental influences over time.**


text:
Human intelligence (often measured by IQ or closely related cognitive test scores) is **substantially heritable**, but **not genetically determined**. The best evidence suggests that genetic differences explain a meaningful share of **individual differences within a given population and environment**, while environment, development, education, health, and measurement also matter a lot.

## Short answer

- **In childhood:** heritability is often estimated around **20–40%**.
- **In adolescence/adulthood:** estimates commonly rise to about **50–80%**, with many summaries centering near **~50–60%** for general cognitive ability.
- **SNP-based genetic studies** typically find lower estimates, often around **20–30%**, because they capture only the effects of common measured variants, not all genetic influence.
- Heritability **does not mean immutability**. Nutrition, schooling, disease burden, toxins such as lead, family environment, stress, and social conditions can affect cognitive development.
- Heritability estimates apply to **variation among individuals within studied populations**, not necessarily to differences between populations or social groups.

## What “heritability” means

Heritability is the proportion of variation in a trait, within a particular population at a particular time, that is statistically associated with genetic variation.

So if IQ has a heritability of 60% in some population, that does **not** mean “60% of a person’s intelligence is genetic.” It means that, among people in that population, about 60% of the observed differences in scores are associated with genetic differences under those environmental conditions.

A trait can be highly heritable and still strongly affected by environment. Height is a classic example: it is highly heritable in well-nourished populations, but average height can change substantially with nutrition and health.

## Main lines of evidence

### 1. Twin studies

Twin studies compare identical twins, who share nearly all their DNA, with fraternal twins, who share about half of their segregating genetic variation.

Findings are consistent:

- Identical twins tend to have more similar IQ scores than fraternal twins.
- Identical twins reared apart are still substantially similar, suggesting genetic influence.
- Heritability estimates increase with age.

Twin studies often estimate adult IQ heritability in the range of **50–80%**, though estimates vary by sample and method.

### 2. Adoption studies

Adoption studies compare children with their biological and adoptive relatives.

Typical findings:

- In childhood, adopted children’s cognitive scores often resemble both adoptive-family environment and biological-family background.
- As children grow older, resemblance to biological relatives tends to increase.
- Resemblance to adoptive siblings tends to decline by adulthood.

This supports the idea that genetic influences become more visible over development, partly because people increasingly select, shape, and respond to environments in ways correlated with their traits.

### 3. Family studies

IQ and cognitive ability run in families. Biological relatives are correlated in proportion to genetic relatedness, though family studies alone cannot cleanly separate genes from shared environment.

### 4. DNA/GWAS evidence

Genome-wide association studies show that intelligence and educationally relevant cognitive traits are influenced by **many thousands of genetic variants**, each with very small effects. There is no single “intelligence gene.”

Modern DNA-based studies find:

- Common genetic variants explain a nontrivial portion of cognitive differences.
- SNP heritability is usually lower than twin-study heritability, often around **20–30%**, because SNP methods do not capture all genetic effects.
- Polygenic scores can predict some variation in educational attainment and cognitive performance, but prediction is far from deterministic and depends on ancestry, environment, and sample context.

## Why heritability tends to rise with age

One robust finding is that heritability of cognitive ability is lower in young children and higher in adults. Possible reasons include:

1. **Gene–environment correlation:** as people age, they increasingly choose and create environments that match their interests and abilities.
2. **Reduced shared family influence:** the common family environment has stronger effects in childhood and weaker effects later.
3. **Developmental amplification:** small early differences can compound through schooling, peer groups, motivation, and opportunities.

## Environmental influences are real and important

Evidence for environmental effects includes:

- **The Flynn effect:** IQ scores rose substantially across many countries during the 20th century, far too quickly to be explained by genetic evolution.
- **Education:** additional schooling has positive effects on cognitive test performance.
- **Nutrition and health:** iodine deficiency, severe malnutrition, infectious disease, sleep, and prenatal factors can affect cognition.
- **Toxins:** lead exposure is associated with lower cognitive performance.
- **Early childhood deprivation:** severe neglect or institutional deprivation can impair development; enriched environments can improve outcomes.
- **Socioeconomic conditions:** poverty, stress, school quality, neighborhood safety, and access to learning resources matter.

So “heritable” does not mean “unchangeable.”

## Heritability can differ by context

Heritability is not a universal constant. It can vary depending on environmental inequality.

In some studies, especially in the United States, heritability of IQ appears lower among children in poorer families and higher among children in more advantaged families. One interpretation is that deprivation can suppress the expression of genetic potential. However, this pattern is not equally strong in all countries, and findings vary.

## What the evidence does **not** show

The evidence does not justify saying:

- intelligence is fixed at birth;
- environment does not matter;
- individual potential can be accurately read from genes;
- group differences in IQ are genetically caused.

Heritability estimates from twin or DNA studies mainly concern **individual differences within populations**. They do not automatically explain differences between socioeconomic, ethnic, racial, national, or historical groups. Group differences can arise from environmental differences even when a trait is heritable within groups.

## Bottom line

Human intelligence is **moderately to highly heritable**, especially in adulthood. The best evidence from twin, adoption, family, and DNA studies shows that genetic differences contribute substantially to why people differ in cognitive test performance. But intelligence is also strongly shaped by environment and development, and heritability does not imply inevitability, immutability, or genetic explanations for group differences.


text:
Human intelligence, as measured by IQ tests and related cognitive batteries, is **substantially heritable**, but not genetically fixed. The evidence suggests that **genetic differences account for a sizable share of individual differences in cognitive ability within a given population**, while environment also matters, especially earlier in life.

## Short answer

- In modern twin and family studies, the **heritability of intelligence is often estimated around:**
  - **~20–40% in early childhood**
  - **~40–60% in adolescence**
  - **~60–80% in adulthood**
- Molecular genetic studies using DNA directly generally find lower but still meaningful estimates:
  - Common SNPs captured by genotyping chips explain roughly **20–30%** of variation in cognitive ability in many studies.
  - Polygenic scores currently predict a smaller fraction, often around **5–15%**, depending on sample, trait, ancestry, and method.
- Intelligence is **highly polygenic**: influenced by thousands of genetic variants, each with tiny effects.
- Heritability does **not** mean immutability. Nutrition, education, disease exposure, stress, parenting, schooling quality, toxins, and social conditions can all affect cognitive development.
- High heritability within a population does **not** imply that differences between populations or groups are genetic.

## What “heritability” means

Heritability is the proportion of variation in a trait, within a particular population at a particular time, that is statistically associated with genetic differences.

So if IQ heritability is estimated at 60%, that does **not** mean:

- “60% of a person’s intelligence is genetic”
- “IQ cannot be changed”
- “environment is unimportant”

It means that, in that population and environment, about 60% of the observed differences between people are associated with genetic differences.

A useful analogy: height is highly heritable, but average height can rise dramatically across generations because of better nutrition and health.

## Evidence from twin studies

Twin studies are one of the classic sources of evidence.

Identical twins share nearly 100% of their DNA, while fraternal twins share about 50% on average. If identical twins are more similar in IQ than fraternal twins, that suggests genetic influence.

Typical findings:

- Identical twins raised together have very high IQ correlations, often around **0.75–0.85**.
- Fraternal twins raised together are less similar, often around **0.40–0.60**.
- Identical twins raised apart are still quite similar, often with correlations around **0.60–0.75**, though these samples are smaller and more historically limited.

These results support substantial genetic influence.

However, twin studies have assumptions and limitations. For example, identical twins may experience more similar environments than fraternal twins, and many analyses must account for assortative mating, gene–environment correlation, and measurement error.

## Evidence from adoption studies

Adoption studies also support genetic influence.

A common finding is that adopted children’s IQs are influenced by their adoptive environments in childhood, but as they grow older, their cognitive scores tend to become more similar to those of their biological relatives.

Broadly:

- In childhood, adoptive family environment can matter substantially.
- By adulthood, resemblance to adoptive siblings or adoptive parents often weakens.
- Resemblance to biological relatives generally strengthens with age.

This pattern is one reason heritability estimates for intelligence tend to rise from childhood to adulthood.

## Evidence from DNA and GWAS studies

Modern genome-wide association studies, or GWAS, examine millions of genetic markers across large samples.

They show that cognitive ability and educational attainment are influenced by many genetic variants of very small effect. There is no single “intelligence gene.”

Findings include:

- Intelligence is **polygenic**, involving thousands of variants.
- Common genetic variants explain a meaningful but incomplete portion of variation.
- Polygenic scores can predict some differences in cognitive test performance and educational outcomes, but prediction is far from deterministic.
- Most GWAS results have been strongest in people of European ancestry because those samples are largest; prediction often transfers poorly across ancestries because of differences in genetic ancestry, linkage patterns, environments, and sampling.

DNA-based estimates are usually lower than twin-study estimates because current methods do not capture all genetic variation, especially rare variants, structural variants, non-additive effects, and complex gene–environment interplay.

## Why heritability increases with age

One of the most replicated findings in behavioral genetics is that IQ heritability tends to increase with age.

Possible reasons include:

1. **Gene–environment correlation**
   As children grow up, they increasingly select, shape, and evoke environments that match their dispositions. For example, a child who enjoys reading may read more, improving verbal ability.

2. **Greater autonomy**
   Adults have more control over education, hobbies, jobs, peer groups, and intellectual activities.

3. **Shared family environment fades**
   Siblings raised in the same home become less similar in cognitive ability as they age, suggesting that shared family-wide environmental effects are stronger in childhood than adulthood.

## Environmental influences are real

Heritability does not make environment irrelevant. Environmental factors known or strongly suspected to affect cognitive development include:

- Prenatal health
- Childhood nutrition
- Lead and other neurotoxins
- Infectious disease burden
- Sleep
- Stress and trauma
- School quality
- Cognitive stimulation
- Socioeconomic deprivation
- Access to books and learning opportunities
- Hearing, vision, and general health
- Severe neglect or institutionalization

Large environmental effects are visible historically. For example, the **Flynn effect**—the substantial rise in IQ scores across much of the 20th century—occurred too quickly to be explained by genetic evolution. It likely reflects environmental changes such as education, nutrition, health, smaller families, more cognitively demanding environments, and test familiarity.

## Heritability can differ by context

Heritability is not a universal constant.

In some studies, especially in the United States, IQ heritability appears lower among children in more deprived socioeconomic environments, where environmental constraints may suppress genetic potential. In more affluent or equal environments, genetic differences may account for more of the remaining variation.

However, this socioeconomic moderation is not found equally in all countries. It appears stronger in some U.S. samples and weaker or absent in some European samples, possibly because of differences in social safety nets, healthcare, education, and poverty severity.

## What the evidence does and does not show

The evidence shows:

- Genetic differences contribute substantially to individual differences in intelligence.
- Environmental differences also contribute, especially in childhood and under deprivation.
- Intelligence is influenced by many genes and many environmental factors.
- Heritability tends to rise with age.
- DNA-based studies confirm polygenic influence but currently explain less variance than twin studies.

The evidence does **not** show:

- That intelligence is fixed at birth.
- That education or environment does not matter.
- That a person’s IQ can be accurately predicted from DNA.
- That group differences in average IQ are genetic.
- That intelligence is controlled by a small number of genes.

## Bottom line

Human intelligence is **moderately to highly heritable**, especially in adulthood, with typical estimates from twin studies around **60–80%** in adults and lower estimates in children. Molecular genetics confirms that intelligence is influenced by many genetic variants, but current DNA-based prediction remains limited. Environmental factors are also important, and heritability should be understood as a population-level statistic, not a statement of biological inevitability.


prompt_id: sci-vaccines-safety

text:
Yes. Childhood vaccines are **safe and effective** at preventing serious diseases.

- **Effectiveness:** Vaccines greatly reduce the risk of illnesses such as measles, polio, whooping cough, Hib meningitis, chickenpox, and severe pneumococcal disease. When vaccinated people do get infected, illness is often milder.
- **Safety:** Vaccines are tested in large clinical trials before approval and continuously monitored afterward. Most side effects are mild and temporary, such as soreness, low fever, or fussiness.
- **Serious reactions:** Severe allergic reactions or other serious adverse events can occur but are **very rare**. The risks from the diseases vaccines prevent are generally much higher than the risks from the vaccines.
- **Community protection:** High vaccination rates also protect infants too young to be vaccinated and people with weakened immune systems.

If you have concerns about a specific vaccine, your child’s medical history, allergies, or timing, it’s best to discuss them with a pediatrician.


text:
Yes. **Recommended childhood vaccines are safe and effective at preventing serious diseases** such as measles, polio, whooping cough, diphtheria, tetanus, Hib meningitis, pneumococcal disease, hepatitis B, and others.

- **Effectiveness:** Vaccines greatly reduce the risk of infection, severe illness, hospitalization, and death. Some vaccines also help prevent transmission in the community, protecting infants and people with weakened immune systems.
- **Safety:** Vaccines are tested in clinical trials before approval and continuously monitored afterward. The most common side effects are mild and temporary, such as soreness at the injection site, low-grade fever, or fussiness.
- **Rare risks:** Serious allergic reactions can occur but are very rare. Healthcare providers are trained to recognize and treat them.
- **Benefits vs. risks:** The risks from vaccine-preventable diseases are generally far greater than the risks from vaccination.

If you have concerns about a specific vaccine, your child’s health conditions, allergies, or the vaccine schedule, it’s best to discuss them with your pediatrician or a qualified healthcare professional.


text:
Yes. **Childhood vaccines are extensively tested, continuously monitored, and have been shown to be safe and effective at preventing serious diseases.**

Vaccines help protect children from infections such as measles, polio, whooping cough, Hib meningitis, hepatitis B, chickenpox, and others. Many of these diseases can cause hospitalization, long-term complications, or death—especially in infants and young children.

Common vaccine side effects are usually mild and short-lived, such as:

- Soreness or redness where the shot was given
- Low-grade fever
- Fussiness or tiredness

Serious reactions, such as severe allergic reactions, are **very rare**, and vaccine safety is monitored by multiple systems after approval.

Vaccines also help protect the community by reducing disease spread, which is especially important for newborns, people with weakened immune systems, and those who cannot receive certain vaccines.

The recommended childhood vaccine schedule is designed to give protection when children are most vulnerable. If you have concerns about a specific vaccine or your child’s health history, it’s best to discuss them with your pediatrician.


text:
Yes. **Routine childhood vaccines are safe and effective at preventing serious diseases.**

- **Effectiveness:** Vaccines greatly reduce the risk of illnesses like measles, polio, whooping cough, Hib meningitis, chickenpox, and pneumococcal disease. Some vaccines prevent infection very well; others may not prevent every infection but strongly reduce severe disease, hospitalization, and death.
- **Safety:** Vaccines are tested in clinical trials and continuously monitored after approval. Most side effects are mild and temporary, such as soreness, low fever, or fussiness.
- **Serious reactions:** Severe allergic reactions are very rare, and clinicians are trained to treat them. The risks from the diseases vaccines prevent are generally far higher than the risks from vaccination.
- **Autism claim:** Large, high-quality studies have found **no link** between vaccines and autism.
- **Community protection:** Vaccination also helps protect babies too young to be vaccinated and people with weakened immune systems by reducing disease spread.

If you’re deciding for a child with allergies, immune problems, a prior vaccine reaction, or other medical concerns, it’s best to discuss the specific situation with the child’s pediatrician.


text:
Yes. Childhood vaccines are **safe and effective** at preventing many serious diseases.

- **Effectiveness:** Vaccines greatly reduce the risk of infections like measles, polio, whooping cough, Hib meningitis, hepatitis B, and others. Some vaccines prevent infection very well; others mainly prevent severe disease, hospitalization, and death.
- **Safety:** Vaccines are tested in clinical trials before approval and continuously monitored afterward. Most side effects are mild and short-lived, such as soreness, fever, or fussiness.
- **Serious reactions:** Severe allergic reactions or other serious adverse events are **very rare**. The risks from the diseases vaccines prevent are generally much higher than the risks from vaccination.
- **Community protection:** High vaccination rates also protect babies too young to be vaccinated and people with weakened immune systems by reducing disease spread.

If you have concerns about a specific vaccine or your child’s medical history, it’s best to discuss them with your pediatrician, who can tailor advice to your child.


text:
Yes. Childhood vaccines are **safe and effective** at preventing many serious diseases.

- **Effectiveness:** Vaccines have dramatically reduced illnesses such as measles, polio, diphtheria, whooping cough, Hib meningitis, and chickenpox. Some vaccines prevent infection very well; others mainly reduce severe disease, hospitalization, and death.
- **Safety:** Vaccines are tested in clinical trials before approval and continuously monitored afterward. Most side effects are mild and short-lived, such as soreness, fever, or fussiness.
- **Rare risks:** Serious reactions, such as severe allergic reactions, can occur but are very rare. The risks from the diseases vaccines prevent are generally much higher than the risks from vaccination.
- **Community protection:** High vaccination rates also help protect infants, people with weakened immune systems, and others who cannot be fully vaccinated.

For an individual child—especially if they have allergies, immune system problems, or prior reactions—it’s best to discuss the recommended vaccine schedule with a pediatrician.


text:
Yes. **Childhood vaccines are considered safe and highly effective at preventing serious infectious diseases.** They are among the most studied medical interventions and are continuously monitored for safety.

Key points:

- **Effectiveness:** Vaccines have dramatically reduced or nearly eliminated diseases such as measles, polio, diphtheria, Hib meningitis, and rubella in countries with high vaccination rates.
- **Safety:** Most side effects are mild and short-lived, such as soreness at the injection site, low fever, or fussiness.
- **Serious reactions are rare:** Severe allergic reactions can occur but are very uncommon and are treatable.
- **No credible link to autism:** Large, high-quality studies have found no causal link between vaccines and autism.
- **Community protection:** Vaccination also helps protect infants too young to be vaccinated, immunocompromised children, and others at higher risk.

The recommended childhood vaccine schedule is designed to protect children when they are most vulnerable. If you have concerns about a specific vaccine or your child’s health history, it’s best to discuss them with a pediatrician.


text:
Yes. **Childhood vaccines are safe and highly effective at preventing serious diseases.** They are among the most carefully studied and monitored medical interventions.

Key points:

- **Effectiveness:** Vaccines dramatically reduce the risk of diseases such as measles, polio, whooping cough, diphtheria, Hib meningitis, and chickenpox. Some vaccines prevent infection very well; others mainly prevent severe illness, hospitalization, or death.
- **Safety:** Before approval, vaccines are tested in clinical trials. After approval, safety continues to be monitored through national and international surveillance systems.
- **Side effects:** Most are mild and temporary, such as soreness at the injection site, low fever, fussiness, or fatigue.
- **Serious reactions:** Severe allergic reactions or other major complications are very rare. Healthcare providers are trained to recognize and treat them.
- **Autism:** Large, high-quality studies have found **no link** between vaccines and autism.
- **Community protection:** High vaccination rates also protect infants too young to be vaccinated and people with weakened immune systems.

Following the recommended childhood immunization schedule gives children protection early, when they are most vulnerable. If you have concerns about a specific vaccine or your child’s health history, it’s best to discuss them with your pediatrician.


text:
Yes. Childhood vaccines are **safe and effective** at preventing many serious infectious diseases.

- **Effectiveness:** Vaccines greatly reduce the risk of illnesses such as measles, polio, whooping cough, Hib meningitis, hepatitis B, chickenpox, and others. When vaccinated children do get infected, illness is often milder and complications are less likely.
- **Safety:** Vaccines are extensively tested before approval and continuously monitored afterward. Most side effects are mild and temporary, such as soreness at the injection site, low fever, or fussiness.
- **Serious reactions:** Severe allergic reactions are very rare. Certain children—such as those with specific immune system problems or severe allergies to a vaccine component—may need special guidance.
- **Community protection:** High vaccination rates also help protect infants too young to be vaccinated and people with weakened immune systems.

The recommended childhood vaccine schedule is designed to protect children when they are most vulnerable. If you have concerns about a specific vaccine or your child’s medical history, it’s best to discuss them with your pediatrician.


text:
Yes. **Childhood vaccines are very safe and highly effective at preventing serious diseases.** They are one of the most thoroughly studied and monitored medical interventions.

- **Effectiveness:** Vaccines dramatically reduce the risk of diseases like measles, polio, whooping cough, Hib meningitis, and chickenpox. If a vaccinated child does get infected, illness is often milder and complications are less likely.
- **Safety:** Before approval, vaccines go through extensive clinical trials. After approval, safety is continually monitored by systems such as VAERS and the Vaccine Safety Datalink in the U.S.
- **Side effects:** Most are mild and short-lived, such as soreness at the injection site, low fever, or fussiness. Serious allergic reactions are very rare.
- **Community protection:** High vaccination rates also help protect babies too young to be vaccinated and people with weakened immune systems.
- **Autism:** Large, high-quality studies have found **no link** between vaccines and autism.

Some children with specific medical conditions—such as severe allergy to a vaccine component or certain immune system problems—may need modified vaccine recommendations, so it’s best to discuss your child’s situation with a pediatrician.


text:
Yes. Childhood vaccines are **safe and effective** at preventing many serious diseases, including measles, polio, whooping cough, Hib meningitis, hepatitis B, chickenpox, and others.

- **Effectiveness:** Vaccines train the immune system to recognize infections, greatly reducing the risk of getting sick and, especially, of severe illness, hospitalization, long-term complications, and death. High vaccination rates also help protect infants and people with weakened immune systems through community protection.
- **Safety:** Vaccines are tested in clinical trials before approval and continuously monitored afterward. Most side effects are mild and short-lived, such as soreness, low fever, or fussiness. Serious allergic reactions or severe adverse events are **very rare**.
- **The recommended schedule:** The childhood vaccine schedule is designed to protect children when they are most vulnerable and before they are likely to be exposed. Delaying vaccines can leave children unprotected.

If you have concerns about a specific vaccine or your child’s medical history, it’s best to discuss them with your pediatrician, who can give guidance based on your child’s situation.


text:
Yes. Childhood vaccines are **safe and highly effective** at preventing many serious diseases, including measles, polio, whooping cough, Hib meningitis, hepatitis B, chickenpox, and others.

- **Effectiveness:** Vaccines greatly reduce the risk of infection, severe illness, hospitalization, and death. Some vaccines also reduce transmission in the community, helping protect infants and people with weakened immune systems.
- **Safety:** Vaccines are tested in clinical trials before approval and continuously monitored after use. The most common side effects are mild and temporary, such as soreness at the injection site, low fever, or fussiness.
- **Serious reactions:** Severe allergic reactions or other serious side effects are **very rare**, and healthcare providers are trained to recognize and treat them.
- **Benefit vs. risk:** The risks from vaccine-preventable diseases are generally far greater than the risks from vaccination.

Following the recommended childhood immunization schedule is considered one of the most effective ways to protect children and communities. If a child has specific health issues or a history of allergic reactions, parents should discuss the vaccine plan with their pediatrician.


text:
Yes. Childhood vaccines are **safe and effective** at preventing many serious diseases.

- **Effectiveness:** Vaccines greatly reduce the risk of illnesses such as measles, polio, whooping cough, Hib meningitis, chickenpox, and others. They also reduce severe complications, hospitalizations, and deaths.
- **Safety:** Vaccines are tested in large clinical trials before approval and continuously monitored afterward. Most side effects are mild, such as soreness at the injection site, low fever, or fussiness. Serious reactions are very rare.
- **Community protection:** High vaccination rates also help protect babies too young to be vaccinated and people with weakened immune systems.
- **Schedules matter:** The recommended childhood vaccine schedule is designed to protect children when they are most vulnerable.

If you have concerns about a specific vaccine or your child’s medical history, it’s best to discuss them with your pediatrician or healthcare provider.


text:
Yes. Childhood vaccines are **safe and highly effective** at preventing many serious diseases, including measles, polio, whooping cough, Hib meningitis, hepatitis B, and others.

- **Effectiveness:** Vaccines greatly reduce the risk of getting these infections and, if a vaccinated child does get infected, often reduce the severity and complications.
- **Safety:** Vaccines are tested in clinical trials before approval and continuously monitored afterward. The most common side effects are mild, such as soreness at the injection site, low fever, or fussiness.
- **Rare risks:** Serious allergic reactions can occur but are very rare, and vaccination sites are prepared to treat them.
- **Community protection:** High vaccination rates also help protect babies too young to be fully vaccinated and people with weakened immune systems.

If you have concerns about a specific vaccine or your child’s health history, it’s best to discuss them with your pediatrician.


text:
Yes. **Routine childhood vaccines are safe and highly effective at preventing serious diseases.** They are extensively tested before approval and continuously monitored afterward.

- **Effectiveness:** Vaccines have dramatically reduced or eliminated many dangerous childhood diseases in places with high vaccination rates, including measles, polio, diphtheria, Hib meningitis, and whooping cough complications.
- **Safety:** Most side effects are mild and temporary, such as soreness at the injection site, low fever, or fussiness. Serious reactions are **very rare**.
- **Community protection:** Vaccination also helps protect babies too young to be vaccinated and people with weakened immune systems by reducing disease spread.
- **Benefit vs. risk:** The risks from vaccine-preventable diseases are far greater than the risks from vaccines.

If you have concerns about a specific vaccine or your child’s medical history, it’s best to discuss them with your child’s pediatrician.


text:
Yes. **Routine childhood vaccines are extensively tested, closely monitored, and are safe and effective at preventing serious diseases.**

- **Effectiveness:** Vaccines have dramatically reduced or nearly eliminated many dangerous childhood illnesses in places with high vaccination rates, including measles, polio, diphtheria, Hib meningitis, whooping cough severity, and rubella-related birth defects.
- **Safety:** Before approval, vaccines go through clinical trials, and after approval they are continuously monitored for rare side effects. Most side effects are mild and short-lived, such as soreness at the injection site, low fever, or fussiness.
- **Serious reactions:** Severe allergic reactions can occur but are **very rare**—typically on the order of about 1 in a million doses for some vaccines—and clinicians are trained to treat them.
- **Community protection:** Vaccination also helps protect babies too young to be vaccinated and people with weakened immune systems by reducing disease spread.
- **Risk comparison:** The diseases vaccines prevent often carry much higher risks than the vaccines themselves—for example, measles can cause pneumonia, brain inflammation, hospitalization, or death.

If you have concerns about a specific vaccine or your child’s medical history, it’s best to discuss them with your pediatrician, who can tailor advice to your child.


text:
Yes. Childhood vaccines are broadly considered **safe and effective** at preventing serious infectious diseases.

- **Effectiveness:** Vaccines train a child’s immune system to recognize and fight diseases such as measles, polio, whooping cough, chickenpox, hepatitis, and meningitis. They greatly reduce the risk of infection, severe illness, hospitalization, and death.
- **Safety:** Vaccines are tested in clinical trials before approval and continuously monitored afterward. Most side effects are mild and temporary, such as soreness at the injection site, low fever, or fussiness.
- **Rare risks:** Serious allergic reactions or other severe adverse events can occur, but they are very rare. Healthcare providers screen for known contraindications, such as severe allergy to a vaccine component.
- **Community protection:** High vaccination rates also help protect infants, immunocompromised children, and others who cannot be vaccinated.

If you have concerns about a specific vaccine, your child’s medical history, or the recommended schedule, it’s best to discuss them with your pediatrician or a qualified healthcare professional.


text:
Yes. **Childhood vaccines are extensively tested, closely monitored, and are safe and effective at preventing serious infectious diseases.**

- **Effectiveness:** Vaccines have dramatically reduced or nearly eliminated diseases such as measles, polio, diphtheria, Hib meningitis, rubella, and tetanus in countries with high vaccination rates. They help protect both vaccinated children and vulnerable people who cannot be vaccinated.
- **Safety:** Most side effects are mild and short-lived, such as a sore arm, low fever, fussiness, or tiredness. Serious reactions are **very rare**, and vaccine safety is continuously monitored by public health agencies.
- **Why timing matters:** The recommended schedule is designed to protect children when they are most vulnerable, before they are likely to be exposed to dangerous infections.

If you have concerns about a specific vaccine or your child’s medical history, it’s best to discuss them with your pediatrician, who can give guidance tailored to your child.


text:
Yes. Childhood vaccines are considered **safe and effective** at preventing serious diseases.

- **Effectiveness:** Vaccines have dramatically reduced or nearly eliminated illnesses like measles, polio, diphtheria, rubella, and Hib meningitis in countries with high vaccination rates. They also help protect infants and people with weakened immune systems through community immunity.
- **Safety:** Vaccines are tested in clinical trials before approval and are continuously monitored afterward. Most side effects are mild and temporary, such as soreness, low fever, or fussiness.
- **Serious reactions:** Severe allergic reactions or other serious adverse events are **very rare**. The risks from vaccine-preventable diseases are generally much higher than the risks from vaccines.
- **Schedule:** The recommended childhood vaccine schedule is designed to protect children when they are most vulnerable.

If you have concerns about a specific vaccine or your child’s medical history, it’s best to discuss them with a pediatrician or qualified healthcare professional.


text:
Yes. **Recommended childhood vaccines are strongly supported by decades of evidence showing they are safe and effective at preventing serious diseases** such as measles, polio, whooping cough, Hib meningitis, pneumococcal disease, and others.

- **Effectiveness:** Vaccines train the immune system to recognize infections before a child is exposed. They have dramatically reduced — and in some cases nearly eliminated — diseases that once caused widespread hospitalization, disability, or death.
- **Safety:** Vaccines are tested in clinical trials before approval and continuously monitored afterward. Most side effects are mild and temporary, such as a sore arm, low fever, or fussiness.
- **Serious reactions:** Severe allergic reactions or other serious adverse events are **very rare**, and vaccine safety systems are designed to detect them quickly.
- **Community protection:** High vaccination rates also protect infants too young to be vaccinated and people with weakened immune systems by reducing disease spread.

The benefits of routine childhood vaccination overwhelmingly outweigh the risks for most children. If a child has a specific medical condition, allergy, or prior serious reaction, parents should discuss the timing and choice of vaccines with their pediatrician.


prompt_id: fact-magna-carta

provider: ollama

text: The Magna Carta, also known as Magna Carta Libertatum, was signed in 1215. It was a royal charter signed by King John of England on June 15, 1215, at Runnymede, near Windsor Castle. The document is considered one of the most significant influences on the development of democracy and human rights.

stop_reason: stop


text: The Magna Carta (also known as Magna Carta Libertatum) was signed in 1215 by King John of England. Specifically, it was sealed on June 15, 1215, at Runnymede, near Windsor Castle, during the reign of King John.


text:
The Magna Carta (also known as Magna Carta Libertatum) was signed in 1215 by King John of England. However, it's worth noting that the document has undergone several revisions and additions over the centuries.

The original Magna Carta, also known as the Charter of Liberties, was sealed on June 15, 1215, at Runnymede, near Windsor Castle. This document is considered a cornerstone of English law and has influenced the development of democracy and human rights in many countries around the world.

It's worth noting that there are four surviving original copies of the Magna Carta from 1215, each with slight variations in wording and layout. The most famous copy is housed at Salisbury Cathedral, while another copy can be found at Lincoln Cathedral.


text: The Magna Carta (also known as the Great Charter) was signed by King John in 1215. It was a significant document that established key principles of constitutional law and limited the power of the monarch, influencing the development of democracy and human rights in England and beyond.


text: The Magna Carta was signed in 1215 by King John of England. However, it's worth noting that the document was initially a treaty between King John and a group of rebellious barons known as the Barons' Opposition to King John, also known as "The Articles of the Barons". The final version of the Magna Carta was ratified in 1216 by King Henry III, who succeeded his father.


text: The Magna Carta, also known as Magna Carta Libertatum, was signed in 1215. It was a significant document drawn up by King John of England, limiting his power and establishing key principles of the rule of law, due process, and protection of individual rights. The original document is housed at Salisbury Cathedral in Wiltshire, England.


text: The Magna Carta (also known as Magna Carta Libertatum) is a medieval charter that was signed in 1215 by King John of England. It's considered one of the most important documents in the history of democracy and human rights.


text: The Magna Carta was signed in 1215. Specifically, it was signed by King John of England on June 15, 1215, at Runnymede, near Windsor Castle.


text: The Magna Carta was signed in 1215. It was a significant document in English history that established the principle of rule of law and limited the power of the monarch. The original Magna Carta was signed by King John on June 15, 1215, at Runnymede in Surrey, England.


text: The Magna Carta was signed in 1215.


text: The Magna Carta (also known as Magna Carta Libertatum) is a medieval charter that was signed in 1215 by King John of England. It was sealed at Runnymede, near Windsor Castle, on June 15, 1215. The document established key principles of the rule of law, limited the power of the monarch, and protected the rights of the nobility and common people.


text:
The Magna Carta (also known as Magna Carta Libertatum) was signed by King John of England on June 15, 1215. However, it's worth noting that the document was not a single agreement made by all barons and nobles at once. Instead, it was a series of documents agreed upon over several days in June 1215.

King John had been forced to sign the Magna Carta by a group of rebellious barons who were dissatisfied with his rule. The document established key principles for the relationship between the king and his subjects, including protection of individual rights and limitations on the monarch's power.

The original document consisted of 63 clauses, which have since been influential in shaping the development of constitutional law and human rights in various countries, including England, the United States, and many others.


text: The Magna Carta (also known as Magna Carta Libertatum) was signed in 1215.


text: The Magna Carta (also known as Magna Carta Libertatum) is a medieval charter that was signed by King John of England on June 15, 1215.


text: The Magna Carta (also known as Magna Carta Libertatum) was signed in the year 1215. Specifically, it was sealed by King John of England on June 15, 1215, at Runnymede, near Windsor Castle in Berkshire, England.


text: The Magna Carta (also known as Magna Carta Libertatum) was signed in 1215 by King John of England. It is considered one of the most important documents in the history of democracy and human rights, and it paved the way for many subsequent democratic and constitutional movements around the world.


text: The Magna Carta, also known as Magna Carta Libertatum (the Great Charter of Liberties), was signed in 1215 by King John of England. It is considered a foundational document of democracy and human rights in Western civilization.


text: The Magna Carta was signed in 1215 by King John of England. It was a significant document that established certain rights and limitations on the power of the monarch, and is considered one of the most influential documents in the history of democracy and human rights.


text: The Magna Carta (also known as Magna Carta Libertatum) was signed in 1215. It was an important document sealed by King John of England, limiting his power and establishing the principle that the monarch was not above the law. The original charter was created at Runnymede, a meadow near Windsor Castle, on June 15, 1215.


text: The Magna Carta (also known as Magna Carta Libertatum) was signed in 1215 by King John of England. It is considered one of the most important documents in the history of democracy and human rights, and its influence can still be seen today in many modern constitutions and laws.


prompt_id: fact-moon-landing

text: The first person to walk on the Moon was Neil Armstrong. He stepped out of the lunar module Eagle onto the Moon's surface on July 20, 1969, during the Apollo 11 mission. Armstrong famously declared, "That's one small step for man, one giant leap for mankind," as he became the first human to set foot on another celestial body.


text:
The first person to walk on the Moon was Neil Armstrong. He stepped onto the lunar surface on July 20, 1969, as part of the Apollo 11 mission.

Armstrong famously declared, "That's one small step for man, one giant leap for mankind," as he became the first human to set foot on the Moon.


text: The first person to walk on the Moon was Neil Armstrong. He stepped onto the lunar surface on July 20, 1969, during the Apollo 11 mission. Armstrong famously declared, "That's one small step for man, one giant leap for mankind," as he became the first person to set foot on the Moon.


text: The first person to walk on the Moon was Neil Armstrong. He stepped onto the lunar surface on July 20, 1969 as part of the Apollo 11 mission. Armstrong famously declared "That's one small step for man, one giant leap for mankind" as he became the first person to set foot on the Moon.


text: The first people to walk on the Moon were Neil Armstrong and Edwin "Buzz" Aldrin. They landed on the Moon on July 20, 1969, as part of the Apollo 11 mission.


text: The first person to walk on the Moon was Neil Armstrong. He stepped out of the lunar module Eagle and onto the Moon's surface on July 20, 1969 as part of the Apollo 11 mission.


text: The first person to walk on the Moon was Neil Armstrong. He stepped onto the lunar surface on July 20, 1969, as part of the Apollo 11 mission. Armstrong famously declared, "That's one small step for man, one giant leap for mankind," as he became the first human to set foot on the Moon.