Common Genetic and Shared Family Environmental Roots of Optimism, Pessimism, and Emotion Regulation: A Lifelines Family Study

Abstract Dispositional optimism is associated with more favourable and pessimism with less favourable life outcomes. However, their familial origins and overlap in genetic and shared environmental influences with related constructs remain poorly understood. This study used a multigenerational extended-family design (N = 40,761), with information on genetic relatedness and shared households, to partition the variance in optimism, pessimism, emotion regulation, and executive functioning, and their covariance, into genetic, shared family environmental, and unique environmental components. Genetic (rG) and shared environmental correlations (rC) were estimated to examine the degree of overlap between genetic or shared environmental influences on two traits. Genetic factors accounted for 16% of variance in optimism and 22% in pessimism. Shared environmental influences accounted for 17% of variance in pessimism, with no evidence of such influences on optimism. Optimism and pessimism showed substantial overlap in genetic and shared environmental influences (rG and rC ~-.75). Genetic influences on optimism and emotion regulation overlapped moderately to strongly, with positive correlations for active/problem-solving strategies and positive rumination, and negative correlations for rumination/catastrophizing and dampening positive emotions. Pessimism showed the opposite pattern, except for positive rumination, with which no genetic correlation was found. Shared environmental overlap with emotion regulation was less widespread, occurring mainly for pessimism. Genetic and shared environmental overlap appears to be mostly specific to emotion regulation rather than reflecting broader cognitive mechanisms. Findings suggest that optimism, pessimism, and emotion regulation may have partially shared aetiological influences and highlight the importance of future longitudinal research to clarify their developmental trajectories. [PREPRINT]