The primary neuropeptides linked to social behaviors are AVP and oxytocin (OXT), which play critical roles in pair bond formation, one of the most important relationships for human mental health (50). Centrally released OXT facilitates social motivations and approach behavior, including maternal nurturing behaviors (51). Vasopressin regulates several male-typical social behaviors, including scent marking, aggression (52), and paternal care (53). The AVP and OXT neural systems are also involved in other social behaviors, including anxiety (54), processing of social cues (55), and social recognition (56). Many of these effects are sex-specific. For instance, AVP has been shown to differentially influence social communication, decreasing it in male subjects and increasing it in female subjects (57). Vasopressin is more influential in male subjects and OXT is more influential in female subjects (58). It is important to consider our finding in the context of the existing literature. The finding most germane to our study supports the notion that alleles increasing AVPR1A expression would decrease marital stability in male subjects (16). It is thus not surprising that the effect sizes for the tests in
