ABSTRACT
One of the first goals of behavioral genetics is to assess the heritable nature of individual differences in behavior. Studies of the genetic basis of social behavior are of obvious relevance to sociobiology. Behavioral genetics is concerned with the inheritance of all behavioral characters, both individual and social. For all practical purposes, individual members of a given inbred strain are genetically identical, whereas members of different inbred strains may differ at many gene loci. A comparison of different inbred strains reared in the same laboratory environment provides a direct test of the importance of gene differences. Although a major-gene effect was found, a relatively large proportion of the genetic variance in the characters is due to segregation of genes at unidentified loci. Most of the genetic variance of fitness characters which have been subjected to directional selection should be nonadditive.
