Personality change in late adulthood: A reciprocal effects modeling approach

Personality traits have been found to undergo changes across the life-span (Roberts et al., 2006). Numerous developmental behavioral genetic studies have decomposed stable and measurement-specific variability in personality... [ view full abstract ]

Personality traits have been found to undergo changes across the life-span (Roberts et al., 2006). Numerous developmental behavioral genetic studies have decomposed stable and measurement-specific variability in personality into independent genetic and environmental components to understand whether genetic influences, environmental influences, or both account for stability and change in personality (Briley & Tucker-Drob 2014), yet no longitudinal twin study to date have explicitly correlated genetic and environmental components that might underlie personality change. Further twin models that assume independence of genetic and environmental components may missrepresent real developmental processes underlying personality development, as these models misspecify how genetic and environmental influences correlate over real time (Beam & Turkheimer, 2013). In this study we tested whether the reciprocal exchange between people and their environments induces stronger gene-environment correlation as people age.

We present a longitudinal twin study of personality development (neuroticism, extraversion, and openness to experience) using samples of MZ and DZ twins from the Swedish Adoption/Twin Study of Aging (SATSA; Finkel & Pedersen, 2004) from 1984 to 2010 (MZ pairs = 589; DZ pairs = 1194). We specified a genetic simplex model that includes parameters that model the reciprocal exchange between DZ twins and their unique environments. The parameter allows for the accrual of within-family gene-environment correlation in DZ twins, which may explain why DZ twins’ personality scores diverge more rapidly than MZ twins’ scores. Results suggest that within-family gene-environment correlation does not explain why DZ twins’ personality scores diverge over time. Within-family differences in personality development appear to be attributed to unique environmental factors. We comment on the conditions under which including phenotype-environment parameters should be tested in longitudinal twin models.