What did the largest genetic study of personality—an analysis by Ted Schwaba and the Revised Genomics of Personality Consortium of up to 1.14 million people across 46 international cohorts—discover about the 1,260 DNA variants associated with the Big Five traits of extraversion,

This study found that personality is highly polygenic: many common DNA variants make individually tiny contributions to the Big Five, rather than there being “genes for” a particular personality. Its results support a meaningful biological component to personality, but not genetic determinism or individual prediction. 12

Genetic findings

• Across 46 cohorts and 611,037 to 1.14 million participants, the consortium identified 1,260 approximately independent, genome-wide-significant variants associated with extraversion, agreeableness, conscientiousness, neuroticism, or openness. 12
• Of these, 824—about 65%—were in loci not previously associated with the relevant personality trait. 2
• Most loci were trait-specific: 82% of genomic regions containing a significant variant were associated with only one Big Five trait. 2
• Common variants together explained roughly 4.8%–9.3% of observed variation in each trait, or 10.5%–16.2% after adjusting for imperfect personality measurement. 5
• Those figures are substantially below typical twin-study heritability estimates, often around 40%–50%. That gap means much inherited influence is not captured by measured common variants and may also reflect rare variants, non-additive genetic effects, measurement differences, and the assumptions built into twin designs.

Family comparisons and what they mean

• Within-family analyses of about 51,000 siblings found that the genetic associations changed little when siblings were compared with one another. 2
• Because siblings share much of their family environment, this result suggests the detected associations are not primarily artifacts of parental education, socioeconomic position, neighbourhood, or other shared-upbringing pathways; they are more consistent with direct biological inheritance. 2
• This is not proof that environment is unimportant. Personality develops through both inherited dispositions and lived experience, including environments that people partly select or evoke.

Linked life outcomes

The study’s genetic correlations and polygenic analyses associated the traits with broad patterns of behaviour and life outcomes; these are associations, not destiny or necessarily direct causal effects. 12

• Conscientiousness: genetic propensity toward higher conscientiousness was linked to better self-rated health, less smoking and other substance use, more physical activity, fewer hospitalizations, and more favourable aging-related outcomes. Earlier evidence likewise links lower conscientiousness to poorer health, higher weight, and greater substance use. 236
• Neuroticism: higher neuroticism was linked to poorer mental health and health-related outcomes, including greater vulnerability to internalizing problems and less favourable health/aging patterns. 23
• Openness: higher openness was linked to greater residential mobility—such as moving away from one’s birthplace or changing residence—and to education-related outcomes. 2

Reciprocal gene–environment processes

• Mendelian-randomization analyses suggested that education may itself increase openness, rather than education merely being an outcome correlated with pre-existing openness. 12
• Changes in body-mass index may in turn affect conscientiousness and neuroticism, consistent with a reciprocal process in which health and social experiences can modify personality over time. 2
• These results illustrate gene–environment interplay: inherited differences can influence experiences and choices, while experiences such as schooling and health changes can feed back into personality. They should not be read as simple one-way genetic causation. 12

Major limitations

• Approximately 95% of the sample had European-like ancestry, so effect estimates and polygenic scores may not generalize well to people with other ancestries, countries, cultural settings, or historical circumstances. 12
• The associations identify statistical links, not single causal DNA mechanisms; a significant variant can tag a broader correlated genomic region.
• Even aggregated polygenic scores explain only a modest share of population-level variation. They cannot accurately predict any particular person’s personality, nor establish what that person will do or become. 25
• The study’s strongest conclusion is therefore population-level: personality has a diffuse, partly inherited genetic architecture that is robust across many cohorts and linked to consequential outcomes, while environmental development and individual unpredictability remain central. 12