It is also possible, however, that intergenerational effects (i.e., the transmission of genetic factors from one generation to the next), in interaction with the environmental influences of parents on their offspring, may be important in the development of psychopathology that is comorbid with alcohol dependence. The example of early childhood trauma (e.g., childhood sexual abuse) and its effects on later risk of psychopathology illustrate this possibility. A history of childhood sexual abuse is associated with an increased risk of alcohol dependence as well as an increased risk of a variety of other psychiatric disorders, including major depression, anxiety disorders, and conduct disorder (e.g., Kessler et al. 1997b). Results from twin studies suggest that this association is at least in part indirect, through other family background risk factors that are correlated with increased risk of abuse. These indirect pathways, which may involve intergenerational effects, are discussed in the following paragraphs. However, a direct association between childhood sexual abuse and subsequent psychopathology is also likely. For example, three studies evaluated twin pairs where one twin had been abused and the other had
