Signs of latent handedness in families

Luria argued that several behaviors suggested a "latent" handedness. He suggested that such things as the way in which one crossed one's arms or clasped one's hands might reflect a latent preference for the left hand. Arm-folding refers to the preferential tendency for individuals to fold one forearm over the other, whereas hand-clasping refers to the preferential tendency for individuals to clasp the hands together. We investigated hand-clasping and arm-folding in 292 families (mother, father, and offspring). In this study about 55% of the population are left-hand-claspers, 44% are right-hand-claspers, and the remaining 1% report that they have no preference or are indifferent. About 54% of the population are left-arm-folders, 42% are right-arm-folders, and the remaining 4% report that they have no preference or are indifferent. Familial data suggest that hand-clasping and arm-folding may be under genetic control: although the data do not fit any straightforward recessive or dominant Mendelian model, they are compatible with the type of model invoking fluctuating asymmetry which has been used to explain the inheritance of handedness. It is possible that hand-clasping and arm-folding as well as leg-crossing may be idiosyncrasies due to or influenced by physical bilateral differences in the hands or arms. All family data including others and mine together (arithmetical sum) suggest a genetic contribution, although environmental influences are also evident.