A common pathway model fitted better than an independent pathway model providing strong theoretical support for a latent dimension of liability to externalizing disorders. We are aware of only one prior test of whether externalizing disorders were best explained by a common pathway model. Consistently with our results, Hicks et al. found that the parent–offspring transmission for externalizing disorders were all mediated through a latent common pathway (Hicks et al. 2004). While our estimates of the heritability of the latent liability to ED were substantial (62 % in males and 76 % in females), they were lower than that reported in both sexes (80 %) in the Hicks et al. study that utilized adolescent twins and their parents (Hicks et al. 2004).
