Panskepp et al have studied two inbred mouse strains whose infants on weaning show high versus low levels of gregarious social behavior, They controlled a host of behavioral variables during the course of adolescent development to demonstrate specific differences in social motivations among juveniles of the two mouse strains — behavioral variations that could only be explained by genetic differences. Young mice from the gregarious strain seek environments that predict the possibility of a social encounter and avoid places where they have experienced social isolation. The review by Devitt edited for this post quotes the senior author Lahvis: "There is an association between high-pitched calls in mice and positive experience. The quality and quantity of the call are tightly associated with the nature of the interaction itself."
As the mice neared sexual maturity, the genetic influence on social behavior ebbed and the animals became much more responsive to social cues such as gender...the initial genetic predisposition apparently gets masked by reproductive maturity.
Their work suggests that genetic influences on juvenile social behavior may be quite distinct from genetic factors that affect adult social behavior, a finding the potentially useful for understanding social evolution, as well as developing more realistic animal models of pervasive developmental disorders, such as autism.