Genetic associations between lateral signs.

Only a few authors examined several lateral asymmetries in families simultaneously. Seven lateralities (handedness, footedness, eyedness, earedness, hand clasping, arm folding and leg crossing) were examined in a sample of 292 biologically related parent-offspring triads and 36 sibling pairs. Analysis of the family data showed a significant association between parents and children in most lateralities. The frequency of left-sidedness increased with the number of left-sided parents. Only in the case of footedness and hand clasping there are no significant correlations. Additionally we investigated the inter-relationship between the lateralities in the parental generation. There is a relative strong relation especially among the functional asymmetries. The study analysed also the genetic association (linkage) according to McManus & Mascie-Taylor (1979) between seven different lateralized characteristics. It is shown that the lateral asymmetries correlate genetically relatively imperfectly with each other comparing the inter-relationship between the lateralities in the parental generation. This implicates a multigenetical and also multifactorial determination of laterality in human being.