The relationship between callosal variation and lateralization in mice is genotype-dependent

The relation between morphological variation of the corpus callosum and variation in the degree of paw preference was investigated in 129/J and BALB/cCF mice. A positive relationship explaining 24% of the variance of paw preference was found in 129/J mice; no such relationship exists in BALB/cCF mice. It is suggested that, since the genetic dissimilarity between these two inbred strains is comparable in magnitude with the genetic dissimilarity between unrelated human subjects, genetic variation may have been an uncontrolled source of heterogeneity in previous human neuropsychological studies.