to high-risk environmental exposures, which then interact with (other) genes that increase risk of depression (see Eaves and Sullivan 2001). Even controlling for alcohol dependence history in cases and control subjects will not remove this association, because it is the alcohol dependence histories of the parents and not of the cases or controls that contribute to the observed association. Furthermore, controlling for reported family history of alcoholism also is likely to be ineffective because such family history reports generally show low sensitivity (e.g., Rice et al. 1995).
