Mating assortment and the liability to substance abuse.

Assortative mating can exert a profound influence on the phenotypic composition of the population since it may result in an increase in the frequency of the genotypes associated with extreme phenotypes. Applied to the risk for a disorder such as substance abuse, this would mean a possibility for an increase in the risk and severity of the disorder in consecutive generations. This paper reviews the theoretical and empirical literature on mechanisms related to mate resemblance for the liability to substance abuse, sources and consequences of such resemblance, and suggests directions for further research.