The current sample comprised individuals from the Virginia Adult Twin Study of Psychiatric and Substance Use Disorders, a longitudinal study of psychopathology in adult twins. The sample was originally identified through the Virginia Twin Registry, and includes Caucasian twins born in Virginia between 1934 and 1974. Data for the current study come from wave 1 of data collection in male twin pairs, a telephone interview conducted 1993–1996 (for recruitment and non-participation details, see Kendler & Prescott, 2006). The current study uses only data from same-sex male twin pairs. We excluded participants from male–female twin pairs because of large differences between sexes in reports of sexual abuse, and we did not assess these childhood maltreatment items in our parallel study of female twin pairs. Participants were informed about the purpose of the study and gave verbal informed consent before interviews.
