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New research published in the Journal of Personality & Social Psychology shows that both personality traits and life satisfaction are significantly more heritable than previously thought.
How much of who we are is inherited from our family? For decades, psychologists have tried to provide a quantitative answer through estimates of heritability. Traditional studies, often based on self-reports from twins, have placed the heritability of the Big Five personality traits around 40-50%. However, these studies may provide only an upper limit, reflecting both genetic and shared environmental influences; they also tend to rely on a single method of measurement.
More recent evidence from studies of ordinary relatives, such as siblings or parents and children, suggests that personality trait similarities are much lower, typically around 15%. This has raised questions about whether twin studies overestimate heritability or whether single-method approaches fail to capture the full picture.
In this study, René Mõttus and colleagues grounded their research in the idea that self-reports often include biases that obscure the “true” familial resemblance. By integrating informant reports (evaluations from people who know the participant well), the researchers aimed to separate genuine trait similarity from methodological noise.
The study used data from the Estonian Biobank, a large-scale, population-based genetic and psychological research project. Participants included 32,004 Estonian-speaking adults (age 17-102, 71% female) who had completed a comprehensive self-report survey on personality and life satisfaction. Importantly, genetic data allowed the researchers to identify relationships among participants, including parent-child, siblings, and second-degree relatives, resulting in 24,118 relative pairs for the main self-report analysis.
A smaller subset of 2,258 participants (1,386 relative pairs) also had informant reports available, where each person was rated by someone close to them (mostly spouses or long-term partners). This dual-source design allowed the researchers to estimate trait similarity based on information shared across raters, what they called “true correlations.” All participants completed a 198-item measure called the 100-NP, which includes Big Five traits and additional dimensions. Life satisfaction was measured with three targeted items and validated against established well-being measures.
Advanced statistical models, including multigroup structural equation modeling, were used to estimate additive genetic influences (heritability) while controlling for biases in single-rater data.
Self-report data alone replicated previous findings. Correlations in Big Five traits between parents and children or siblings hovered around 0.13 to 0.15. For second-degree relatives, correlations were even smaller, around 0.07. This suggests that familial resemblance in personality is modest when relying solely on self-assessments.
However, when using the multimethod design, “true correlations” (based on shared variance across self- and informant reports) were considerably higher. Parent-offspring correlations averaged around 0.25, and sibling correlations about 0.20—roughly 35-50% higher than single-method estimates. These true correlations translated into narrow-sense heritability estimates of around 42% for personality traits and 47% for life satisfaction—substantially higher than the 26% estimated from self-reports alone.
Furthermore, life satisfaction was just as heritable as personality traits and shared about 80% of its genetic variance with neuroticism, extraversion, and conscientiousness. Nearly half of life satisfaction’s correlation with these traits was genetically driven.
Notably, there was little evidence that shared family environments influenced these traits. Second-degree relatives who did not grow up together were just as similar as those who did, reinforcing the view that familial resemblance stems primarily from genetics, not upbringing.
The authors acknowledge that despite efforts to isolate true trait similarity, the generalizability of the findings may be constrained by sample composition (primarily Estonian participants) and reliance on informants who were not randomly assigned, which may introduce its own biases.
Overall, this study underscores that life satisfaction and personality are more strongly shaped by genetics than commonly reported, and highlights the value of multimethod designs for accurately estimating psychological heritability.
The study, “Familial Similarity and Heritability of Personality Traits and Life Satisfaction Are Higher Than Shown in Typical Single-Method Studies,” was authored by René Mõttus, Christian Kandler, Michelle Luciano, Tõnu Esko, Uku Vainik, and the Estonian Biobank Research Team.
