Gene-environment processes linking peer victimization and physical health problems: a longitudinal twin study.

Objective: This study examined whether (a) a genetic disposition for physical health problems increases the risk of peer victimization and (b) peer victimization interacts with genetic vulnerability in explaining physical health problems.

Methods: Participants were 167 monozygotic and 119 dizyogtic twin pairs. Physical symptoms were assessed in early childhood and early adolescence. Peer victimization was assessed in middle childhood.

Results: Genetic vulnerability for physical health problems in early childhood was unrelated to later peer victimization, but genetic vulnerability for physical health problems during early adolescence increased the risk of victimization. Victimization did not interact with genetic factors in predicting physical symptoms. Environmental, not genetic, factors had the greatest influence on the development of physical symptoms in victims.

Conclusion: Genetic vulnerability for physical health problems in early adolescence increases the risk of peer victimization. Whether victims suffer a further increase in physical symptoms depends on the presence of protective environmental factors.