Differential Psychology

Differences in the extent to which individual personality trait levels remain the same or change over time result from genetic and environmental factors and their interplay. Environmental factors can induce changes in the expression of genes, known as epigenetic changes. As epigenetic changes might be related with age (i.e., epigenetic aging), they could also influence personality change over time. Conversely, personality differences could influence individual experiences that accelerate or decelerate epigenetic aging.

Based on data from the German twin family panel TwinLife and the TwinLife Epigenetic Change Satellite (TECS) project, we explored patterns, sources, and links of epigenetic aging and Big Five personality trait differences. Information on epigenetic aging was derived from saliva-based DNA methylation and on personality traits from self-reports. Data from two timepoints around 2.3 years apart from 1,088 early adolescent to young adult twins were considered.

Longitudinal statistical model analyses revealed significant mean-level acceleration in epigenetic aging and decreases in all personality traits except neuroticism. Differences between individuals in their intraindividual change were mainly driven by environment. Acceleration in epigenetic aging over time was associated with higher baseline agreeableness and conscientiousness and with decreases in conscientiousness over time. At baseline, more accelerated epigenetic aging was related with lower conscientiousness. Links involving stable personality differences were primarily genetic. The link between changes in epigenetic aging and conscientiousness was almost completely environmental.

Conscientiousness turned out to be the most robust personality correlate of epigenetic aging. We discuss the findings within a framework of gene-environment interplay underlying stable differences and change of epigenetic aging and personality traits.

Link to the full article: https://journals.sagepub.com/doi/10.1177/08902070261418426