Sex-dependent features of social behavior differ between distinct laboratory mouse strains and their mixed offspring

The survival of individuals of gregarious species depends on their social interactions. In humans, atypical social behavior is a hallmark of several psychopathological conditions, many of which have sex-specific manifestations. Various laboratory mouse strains are used to reveal the mechanisms mediating typical and atypical social behavior in mammals. Here, we used three social discrimination tests to characterize social behavior in males and females of three widely used laboratory mouse strains (C57BL/6J, BALB/c, and ICR). We found marked sex- and strain-specific differences in the behavior exhibited by subjects, in a test-dependent manner. Interestingly, some characteristics were strain-dependent, while others were sex-dependent. We then crossbred C57BL/6J and BALB/c mice and found that offspring of such crossbreeding exhibit social behavior which differs from both parental strains and depends on the specific combination of parental strains. Thus, social behavior of laboratory mice is sex- and strain-specific and depends on both genetic and environmental factors.