Selection of control families was based on availability of a pair of same sex adult siblings. Selection of families was based on one of two methods. In the first method (Control Group I – CPFFS Study), volunteers were screened for Axis I psychopathology including alcohol and drug dependence using the DIS. Control families were selected if the volunteer’s first-degree relatives (parents and siblings) were similarly free of psychopathology. In the second method (Control Group II – BRFFS Study), volunteers from the same census tract who indicated they had children between the ages of 8–18 years were screened as a potential control family in order to match the family to a high-risk family using census tract information. The control parents of these offspring were screened for parental alcohol or drug dependence. Previous comparison of control groups I and II did not reveal significant differences in socioeconomic or in offspring rates of psychopathology in the two control groups (See Hill et al., 2008 for details), allowing the control groups to be merged for the present analyses.
