use only among those with the high risk DRD4 allele, but not in those with two low risk alleles. Regardless of DRD4 genotype, the results revealed a developmental pattern of peer influence on both alcohol use and heavy drinking from late adolescence to emerging adulthood, accompanied by peer selection for similar levels of alcohol use and/or heavy drinking from adolescence throughout later young adulthood. Finally, the results indicated lower continuity in friends' alcohol use, as well as own alcohol use and heavy drinking during the transition from adolescence to emerging adulthood, followed by greater continuity in all constructs throughout emerging and young adulthood.
