When we examined biometrical moderation of internalizing psychopathology by marital quality, a more complex picture emerged, detailing the contribution of genetic and environmental influences on internalizing as functions of marital relationship quality. Specifically, genetic influences were of greater importance in the etiology of the internalizing spectrum where levels of marital quality were low. These results suggest that adults with a genetic liability to internalizing spectrum syndromes may be at greater risk of developing symptoms when they are in an unsatisfying marriage. Considering only the static parameter estimates from a no-moderation bivariate model, the etiology of internalizing appeared largely to be due to substantial non-shared environmental influences and similar modest contributions from genetic and shared environmental factors. From the moderation models, we see that people at the extreme low end of marital quality reported a level of internalizing that reflects a genetic sensitivity to pathology. Both the total phenotypic variance and the heritability of internalizing were generally highest at low levels of Quality. Thus, it seems that being low in positive relationship quality allows for the expression of a genetic predisposition to internalizing symptoms.
