Importantly, the estimated correlation between the latent internalizing and externalizing genetic factors in Model 3 was r=.89, suggesting that many of the same genetic factors influence variability in the psychopathology dimensions in both the internalizing and externalizing domains. Based on this revealing observation, Model 4 was formulated to test the addition of a third higher-order genetic factor on which all psychopathology dimensions loaded, termed “global psychopathology.” Correlations among the global, internalizing, and externalizing factors were set to 0 in Model 4. As reported in Table 3, Model 4 fit significantly better than the two-factor model (i.e., Model 3), suggesting that, in addition to the higher order internalizing and externalizing factors, there is a global genetic factor that influences variability in all 11 psychopathology dimensions. Model 5, which allowed the internalizing and externalizing factors to correlate, fit significantly better than Model 4.
