One of the most important challenges to studies of the intergenerational transmission of alcoholism is the well‐documented spousal concordance for alcohol use and disorders. 149 , 150 , 151 , 152 Previous work in COGA as well as numerous other studies have shown greater than expected prevalence of AUD in spouses of probands with AUD. 124 , 153 Assortative, or non‐random, mating refers to deviations from random mating patterns due to mating preference for phenotypically similar (or dissimilar) partners more than expected by chance. This phenomenon has been well documented for psychological traits, psychiatric disorders and substance use disorders 149 , 152 , 153 , 154 and their comorbidity. 149 , 154 , 155 Furthermore, systematic cross mating patterns (e.g., males with alcohol use disorders and females with mood and/or anxiety disorders) may lead to erroneous inferences regarding shared genetic variance of two or more conditions. 150 , 154 , 156
