Lifetime use and age at first use of alcohol, cigarettes, and cannabis were assessed in the offspring interview. History of alcohol intoxication and regular smoking were also assessed. Onset of regular smoking was coded from age at first regular use of cigarettes, the latter defined as a) having smoked 100 or more cigarettes, or b) smoking between 20–99 cigarettes and having smoked at least once per week for a period of two months or more.
