Females have substantially lower rates of all externalizing psychopathology compared to males (Compton et al. 2007; Hasin et al. 2007; Kessler et al. 1994). Because of our large sample size, we have an opportunity to explore sex effects in genetic influences of externalizing disorders in more detail than has been possible in prior genetically informative studies (Hicks et al. 2004; Kendler et al. 2003, 2011).
