Socioregional or neighborhood-level influences have also been reported to moderate the importance of genetic influences on substance use. Genetic influences for late adolescent alcohol use and early adolescent behavior problems are enhanced in urban environments, communities characterized by greater migration, and neighborhoods with higher percentages of slightly older adolescents/young adults (Rose, Dick, Viken, & Kaprio, 2001; Dick, Rose, Viken, Kaprio, & Koskenvuo, 2001a; Dick et al., 2009). These moderation effects presumably reflect differences in availability of alcohol, role models, neighborhood stability, and community-level monitoring across different areas. Indeed, twin studies suggest that many of the important moderating effects of the environment associated with alcohol use and related externalizing behavior reflect differences in situational constraints and/or opportunities, as discussed above, but this type of GXE has been largely unexplored in measured gene studies.
