INTRODUCTION: Adolescents' sibling relationships may serve as a training ground for couple relationships given their similar features, including companionship, closeness and role structure. This study used a dyadic approach to examine sibling intimacy and control in adolescence as predictors of young adults' couple relationship orientations (attachment avoidance and anxiety and attitudes toward marriage). Additionally, research documenting the significance of an other-sex sibling for adolescents' romantic competence guided tests of sibling dyad sex constellation as a moderator of links between sibling relationships and couple relationship orientations in our predominantly heterosexual sample of youth.
METHOD: Firstborns and secondborns from 151 families (Time 1 ages M = 16.42, SD = 0.79 and M = 13.83, SD = 1.14, respectively) reported on their sibling relationships in three annual home interviews and on their couple relationship orientations in web surveys ten years after Time 1.
RESULTS: Estimating actor-partner interdependence models revealed negative effects of sibling intimacy and positive effects of control toward sibling on avoidant attachment, and positive effects of control toward and by sibling on anxious attachment. Sex constellation moderated the interaction effects of the two siblings' intimacy reports on attitudes toward marriage: Mutual high intimacy among mixed-sex dyads predicted more positive attitudes; among same-sex dyads, adolescents' own intimacy compensated for siblings' lower intimacy in predicting positive attitudes toward marriage. Findings emerged with parent marital love controlled.
CONCLUSION: Findings suggest long-term effects of sibling relationships on couple relationship orientations and demonstrate the benefits of using dyadic approaches to examine the implications of sibling relationships.
