In rodent behavior genetic models of drinking, cross-fostering designs (where the genetic background and rearing environment are experimentally crossed) can be extremely informative for identifying relevant environments and GXEs. Within the limitations to interpretation discussed above, animal models could be used to study the effects of maternal and peer environments on adult drinking. Randall (Randall and Lester, 1975a) compared two inbred mouse strains well known to differ in alcohol preference, the high drinking C57BL/6 strain and the low-drinking DBA/2 strain. She cross-fostered some DBA/2 newborns at birth to C57BL/6 mothers, and vice versa. Mice were tested at adulthood for two-bottle alcohol preference drinking. The strong main effect of genotype was clearly seen (C57BL/6 drank more than DBA/2), however, DBA/2 mice reared by a C57BL/6 dam drank more than those reared by a different DBA/2 dam. Thus, there was a clear GXE effect on adult drinking between genotype and postnatal environment.
