Next, we fit a biometric factor model to estimate the genetic and environmental influences on the general externalizing liability, as well as disorder specific genetic and environmental liabilities (Figure 2). The general externalizing factor was highly heritable (a2 = 0.61, 95% CI = 0.50-0.71), but also exhibited significant shared environmental influences (c2 = 0.20, 95% CI = 0.10-0.29), with the remaining variance attributable to non-shared environmental influences (e2 = 0.19, 95% CI = 0.16-0.23).
