abuse was assessed by asking participants if they were ever forced into sexual intercourse or sexual activity before the age of 18. (d) Family history of suicide was determined by having participants report on whether one of their relatives had ever committed suicide. (e) Family history of excessive alcohol use was assessed by asking participants if they have ever felt that either their biological mother or father was an excessive drinker. Notably, family history of suicide and excessive drinking were not included in the discordant twin analyses, because twins are matched for family history. In addition, a (f) Risky Behavior count variable was created via summation of four endorsed risky behaviors including marijuana use, operationalized as using the drug, even once, during the lifetime; early smoking, defined as smoking a cigarette at least one day a week for a period of three weeks or more; early sex, assessed by asking participants the age of first voluntary sexual intercourse; and conduct problems, defined as the presence of one or more conduct disorder symptoms (e.g., physical fighting, hurting animals, shoplifting). From this count variable, four dummy coded variables were created (all 4; 3 only; 2 only; 1 only). Lastly, gender was also
