“…Existing research on the etiology of aggressive behavior in childhood and adolescence has focused on examining biological (including genetic) and environmental factors in families (e.g., Liu, Li, & Guo, ; Marshall, Feinberg, Jone, & Chote, ), but there also has been considerable emphasis on peer group and relationship influences (e.g., Neal & Cappella, ; Walcott, Upton, Bolen, & Brown, ; Xie, Farmer, & Cairns, ). This is because peer groups and their social interactions play a critical role in adolescents’ socialization, including expression of prosocial and aggressive behavior (Dishion, Ha, & Veronneau, ; Harris, ).…”