Sibling Delinquency Revisited: In the Shadows of Mutual and Unique Friendship Effects?

Dana L. Haynie, University at Albany
Suzanne McHugh, University at Albany

Using a standard behavioral genetic model, the DeFries-Fulker regression equation (1985), this study draws on a large sample of genetically related pairs of adolescents from the National Longitudinal Study of Adolescent Health to examine the influence of sibling deviance on adolescents participation in smoking, drinking, truancy, and fighting. This study goes beyond prior research by comparing sibling influence to influence from mutual friends shared between siblings and influence from unique friends that differentiate siblings. This allows for consideration of both unique and shared peer effects that have been unexamined. Combining sibling data with friendship nomination data provided by each adolescent allows for an examination of whether mutual and unique friends' deviance, parental relationship, or sibling relationship factors mediate or moderate sibling influence. Findings from this study indicate that sibling deviance is associated with an adolescent's deviance ( r=.35), with mutual friends' deviance (r=.19), and with unique friends' deviance (r=.42). Further, when siblings nominate mutual best friends (37% of the sample), the bivariate association between mutual friends' deviance and respondents' increase (r=.38) as does the correlation between siblings' deviance (r=.50). A similar increase is noted when respondents' nominate their sibling as being part of their friendship network. Multivariate analyses that control for genetic relatedness indicates that sibling deviance remains associated with self-reported deviance after mutual friends' deviance and unique friends' deviance are accounted for. This suggests that all three sources of influence operate independently. Parent-relationship factors do not mediate these relationships, although there is evidence that sibling affection somewhat mediates the effect of sibling deviance. Moreover, having stronger friendships with siblings conditions the sibling-deviance association so that friendship-like relationships between siblings increase sibling influences. Sibling influence is also strengthened when adolescents' are enmeshed in a friendship network comprised of deviant peers.

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Updated 05/20/2006