Sibling bullying at 12 years and high-risk behavior in early adulthood: A prospective cohort study.

Emerging evidence suggests that sibling aggression is associated with the development of high-risk behavior. This study investigated the relationship between sibling bullying perpetration and victimization in early adolescence and high-risk behavior in early adulthood. Sibling bullying was assessed at 12 years in 6,988 individuals from the Avon Longitudinal Study of Parents and Children, a birth cohort based in the UK and high-risk behavioral outcomes were assessed at 18-20 years. Frequent sibling bullying perpetration predicted antisocial behavior (OR = 1.74; 95%CI, 1.38-2.20), while frequent sibling bullying victimization increased the odds of nicotine dependence (OR = 2.87; 95%CI, 1.55-5.29), even after accounting for peer bullying and parent maltreatment. Categorical analysis revealed that particularly bullies and bully-victims were at risk of developing high-risk behavior. Finally, this study found that adolescents who were involved in bullying perpetration across multiple contexts (home and school) had the highest odds of reporting antisocial behavior (OR = 3.05; 95%CI, 2.09-4.44), criminal involvement (OR = 2.12; 95%CI, 1.23-3.66), and illicit drug use (OR = 2.11; 95%CI, 1.44-3.08). Findings from this study suggest that sibling bullying perpetration may be a marker of or a contributory factor along the developmental trajectory to antisocial behavior problems. Intervention studies are needed in order to test whether reducing sibling bullying can alleviate long-term adverse social and behavioral outcomes.