Family relationships are important predictors of adolescents' diet, physical activity, and health issues including obesity. Despite their prominence in the family, siblings have received little attention on how they may influence these health-related behaviors. Addressing this gap, the present study examined associations between sibling relationship qualities and adolescents' health attitudes, exercise behaviors, and weight controlling for other family relationship qualities. Participants included one parent and two adolescent siblings (ages 12 to 19) from 326 families. Multilevel models indicated that net of parent-adolescent relationship qualities and adolescents' personal characteristics, sibling intimacy was related to healthy attitudes and greater exercise behaviors, whereas sibling conflict was associated with increased risk of being overweight. Links between sibling conflict and weight status, however, were further qualified by gender composition of the sibling dyad. Results highlight the significance of sibling relationships in adolescents' everyday health attitudes and behaviors and implications for intervention efforts are discussed.
Keywords: adolescence; exercise; family relationships; health; obesity; sibling relationships.