Genetic liability can also play a role in shaping the individual’s environment, in the sense that genetically influenced temperamental and personality characteristics lead individuals to select into particular environments. For example, twin studies indicate that part of the relationship between an individual’s substance use and that of their peers is the result of common genetic influences (Edwards et al., 2015b, Harden et al., 2008), suggesting those at heightened risk are more likely to select into environments that will exacerbate any predisposition. This effect is also seen in young adulthood where the effect of marriage on reduction in antisocial behaviors is attenuated after adjusting for common genetic influences (Barnes & Beaver, 2012).
