Twin studies have shown that conduct disorder shares genetic influences with other externalizing disorders, including alcohol and other substance use disorders (Kendler et al., 2003; Krueger et al., 2002; Slutske et al., 1998; Young et al., 2000). This suggests that there are likely to be some genes that have pleiotropic effects, meaning that one gene may be associated with multiple externalizing disorders. Researchers have capitalized on this shared genetic architecture in analyses that examine whether genes identified for other externalizing disorders also influence conduct disorder.
