observed among comparison family participants (34.6% vs. 16.6%). There is considerable addiction comorbidity among the probands, particularly for cannabis and cocaine where 44.9% and 48.4% met dependence criteria respectively. Comorbidity with other substance dependence is less pronounced among their relatives, where 14.2% and 11% met criteria for dependence on cannabis and cocaine, respectively. The prevalence rates in probands and their relatives were markedly higher than those observed among comparison family participants, where only 5.4% met criteria for cannabis dependence, and 1.4% for cocaine, with rates negligible for the other drugs. In contrast to comparison family participants, prevalence of non‐substance disorders comorbidity was elevated among probands and their relatives; for example, prevalence estimates for major depression were 54%, 33.1%, and 22.9% for probands, relatives and comparison participants, respectively, and for conduct disorder 29.6%, 11.4% and 6.2% for proband, relatives and comparison participants, respectively. The children, most of whom were members of case families (i.e., related to probands), were on average about 12 years old and in 6th grade, younger than those in the comparison families, and substance use initiation was not yet a common behavior. The lower prevalence of substance involvement among case family children compared with their comparison family counterparts
