In the area of substance use, twin studies yield consistent evidence for GxE effects associated with environments that differ in the degree to which they offer greater opportunity for substance use or exert social control (Shanahan & Hofer, 2005; Dick, 2011; Kendler, 2011). Additionally, the salience of different environments may also vary across the lifespan. In adolescence, twin studies have demonstrated that genetic influences on alcohol outcomes are higher in environments characterized by low levels of parental monitoring/knowledge (Miles et al., 2005) and higher levels of peer deviance (Dick et al., 2007b, Harden et al., 2008, Li et al., 2017). Neighborhood characteristics that increase opportunity and limit control, such as a higher percentage of young adults in the neighborhood (presumably offering greater access to alcohol and social modeling), and a higher percentage of migration in and out of the community (reflecting neighborhood instability) were associated with greater genetic influences on alcohol outcomes (Dick et al., 2001). As individuals transition into adulthood, other aspects of one’s environment become more important. For example, involvement in romantic partnerships limits genetic influences on alcohol
