The twin interview was based on the Diagnostic Interview for Children and Adolescents (DICA; Reich, 2000) and the C-SSAGA (Semi-Structured Assessment of the Genetics of Alcoholism-Child Version), and was adapted for telephone administration. In addition to covering their own histories of alcohol and smoking problems and various psychiatric disorders, twins were asked to report on smoking patterns of each parent (i.e., “Is your mother or father a current smoker?” and “If your mother or father has quit smoking, did they used to smoke at least 1 or 2 days a week?”). If either of these two questions were answered positively, the parent in question was considered to be a regular smoker.
