How genetic and environmental variance in personality traits shift across the life span: Evidence from a cross-national twin study.
Level 4 - case-series / case-control
Cross-sectional pooled twin study (graded by design analogy, not clinical CEBM)
PubMed 32969676 · doi:10.1037/pspp0000366
What was done
Researchers pooled four twin cohorts from Croatia, Finland, Germany, and the United Kingdom (total N = 7,026; age range 14 to 90 years) to assess linear and non-linear age trends in genetic and environmental variance components across the six HEXACO personality traits (Honesty-Humility, Emotionality, Extraversion, Agreeableness, Conscientiousness, and Openness), adjusting for gender and country differences.
What was found
The abstract reports directional trajectories without specific numerical variance estimates: - Genetic variance displayed an inverted (reversed) U-shaped pattern across age for Extraversion, Agreeableness, and Openness. - Genetic variance showed a declining age trend for Honesty-Humility and Conscientiousness. - Genetic variance remained stable across age for Emotionality. - For most traits, the relative contribution of environmental influences (life experiences) to personality differences increased across the life span.
Why it matters
This study shows that the heritability of personality is dynamic rather than fixed across the lifespan, supporting models of cumulative environmental influence and gene-environment interplay in adult development.
Limits
The abstract provides no point estimates, percentages of variance explained, or confidence intervals. Lifespan trajectories were derived from cross-sectional age comparisons rather than longitudinal tracking of individuals, which risks confounding true developmental changes with birth cohort effects. The sample is limited to European nations, constraining generalizability to other populations.
Cited by
- contradicts The heritability of personality traits continues to increase with age until around age 30.