PARENT AND SIBLING INFLUENCES ON ADOLESCENT ALCOHOL-USE AND MISUSE - EVIDENCE FROM A US ADOPTION COHORT

Objective: Although adolescent alcohol use has been consistently assoc iated with parental drinking behavior, sibling drinking behavior and f amily functioning, the extent to which these associations owe to genet ic or shared environmental influences has not been previously investig ated. Using an adoption study design, we sought to determine whether t he familial correlates of adolescent alcohol involvement were due to c ommon genetic or common environmental effects. Method: The sample cons isted of 653 adopted families ascertained through adoption agencies in four U.S. states. Each family consisted of a target adopted adolescen t, an adoptive mother and an adoptive father. In addition, 68 birth ad olescents (i.e., biological offspring of the adoptive parents) and 187 second adopted adolescents from these families participated in the st udy. All participants completed a mail survey that included assessment of drinking behavior and family functioning. Results: The relationshi p between parental problem drinking and adolescent alcohol involvement was moderate and significant among birth offspring (corrected multipl e correlation, R(C) = .30), but small and nonsignificant among adoptiv e offspring (R(C) = .00). The relationship between adolescent alcohol involvement and family functioning was substantial for birth offspring (Re = .39), but only modest for adoptive offspring (R(C) = .16). The nonbiological sibling correlation for involvement with alcohol was sig nificant (r = .24) and moderated by sibling pair demographic similarit y, such that same-sex, similar-age siblings were substantially more si milar (r = .45) than opposite-sex, dissimilar-aged siblings (r = .01). Conclusions: These findings suggest that adolescent alcohol use is af fected minimally by the environmental consequences of parent problem d rinking and family functioning, but substantially by sibling environme ntal effects.