Several authors consider high and frequent conflicts between friends during childhood as a serious risk for subsequent conduct problems such as generalized physical aggression toward others (e.g., Kupersmidt, Burchinal, & Patterson, 1995; Sebanc, 2003). Although it seems logical to assume that friendship conflict could have some negative…

For pairs of full siblings, half-siblings, and cousins, analyzed maternal ratings of children's behavior problems at three times between ages 4 and 10. Found that nonshared environmental influences were substantial at each age but did not contribute to continuities in children's problem behaviors. Results favor a liability model that relates…