Fourth, less pronounced sex differences were seen in the internalizing spectrum than in the externalizing spectrum. In both men and women, the internalizing genetic common factor was best tapped by a lifetime history of MD and GAD. The largest sex difference was for PD, which was a much better index of the genetic risk for the internalizing dimension in women than in men. In addition, surprisingly, N was a better index of the genetic common factor for the internalizing spectra in males.
