In line with previous research (Spotts et al., 2004a; Spotts et al., 2005b), we found overlap between the genetic influences on marital quality and mental health, represented here by a factor of internalizing pathology. This finding may support a directional link in which internalizing pathology leads to disrupted marital relations. Conversely, it might indicate that an underlying personality dimension or temperament, perhaps of high negative affectivity, influences both internalizing pathology and the quality of the marital relationship. For instance, a person with a predisposition toward higher levels of negative affect or neuroticism may evoke negative reactions from his or her spouse, which may then trigger an internalizing syndrome disorder. In contrast to research that found overlapping non-shared environmental influences shared between marital quality and well-being and depression (Spotts et al., 2004a; Spotts et al., 2005b), we found virtually no unique environmental influences common to marital quality and internalizing pathology. The finding that these two variables are connected solely through genetic influences common to both is strong support for the influence of a distress- and worry-prone personality that contributes to disrupted marital relationship and an internalizing disorder.
