Personality stability and change are not only attributable to net contributions of genetic and environmental factors but also to their interplay. Environmental factors can accelerate or decelerate age-related changes in the expressions of genetic factors (i.e., epigenetic aging), which might influence personality change. Conversely, personality differences could drive experiential differences that accelerate or decelerate epigenetic aging. This study explored the associations between epigenetic aging and Big Five personality traits considering (sources of) stable and change differences. We analyzed saliva-based DNA methylation data on chronological and biological clocks and self-reported personality data from 1,088 early adolescent to young adult twins from two timepoints 2.3 years apart. (Biometric) latent change analyses revealed significant mean-level acceleration in epigenetic aging over time and decreases in personality traits except neuroticism, with variance in intraindividual changes mainly driven by environment. Acceleration in epigenetic aging based on chronological clocks was associated with higher baseline agreeableness and conscientiousness and decreases in conscientiousness. Epigenetic aging based on biological clocks and conscientiousness were negatively related at baseline. The links involving stable personality differences were rather genetic and the change correlation primarily environmental. Findings are discussed considering epigenetic aging and personality differences in a system of interacting genetic and environmental factors.
Instinske et al. (Tue,) studied this question.