Life events and depressive symptoms in childhood--shared genes or shared adversity? A research note.

A twin study design was used to examine to what extent genetic and environmental factors mediate the association between life events and depressive symptoms. Questionnaire measures (maternally rated) of depressive symptoms and life events were obtained for a systematically ascertained sample of 270 twin pairs aged 8 to 17 years. Bivariate genetic model fitting showed that depressive symptoms and some life events (total events, negative impact) share a common genetic influence. The covariation of independent life events and depressive symptoms was explained by a shared environmental influence common to both. At least part of the association between life events and depressive symptoms is mediated by familial factors that include both genes and shared environment.