(ages 15 to 19), parallel to the effect reported for alcohol use at age 18 with slightly older young adults (ages 20 to 24; grouping predetermined by SuomiCD statistics). The fact that we find parallel moderation effects associated with neighborhoods on behavior problems in early adolescence, but not on alcohol use, is also interesting in light of the literature suggesting that early behavior problems share a genetic predisposition with adult alcohol problems (Kendler et al., 2003; Krueger et al., 2002; Slutske et al., 1998), and may represent an earlier manifestation of a predisposition to adult alcohol dependence that manifests as behavior problems even prior to involvement in and establishment of alcohol use patterns (Dick et al., 2006). Our finding that neighborhood factors that moderate influences on alcohol use in late adolescence show parallel effects on behavior problems at age 12, but no effects yet on alcohol use at age 14, may further support this idea. We also note that behavior problems as measured at age 12 already show a substantial heritability (50 to 60%), compared to alcohol use at age 14, which is still largely influenced by common environment.
