Alcohol and Substance Use in Adolescence and Young Adulthood: The Role of Siblings

Interpersonal relationships within and outside the family have been a central part of alcohol and substance use research. Many studies have focused on the role of parents and peers; fewer studies have focused on siblings. This article examines siblings' roles in alcohol, tobacco, and other drug (ATOD) use patterns and trajectories in the context of familial and nonfamilial factors across time. First, intraclass correlations were used to examine the degree to which older siblings' ATOD use was associated with younger siblings' ATOD use. Second, hierarchical regression analyses were conducted to examine the degree to which individual, parent, sibling, and peer factors over time were associated with adolescents' and young adults' ATOD use. It should be noted that developmentally proximal predictors were utilized in these models and within-family replication was also examined. Results demonstrate strong associations between older and younger siblings' ATOD use. Moreover, the developmentally proximal sibling variables were predictive of younger sibling ATOD use in the context of other variables across all substances. Study findings are discussed in terms of identifying promising and potentially malleable points of intervention for future investigators.