Arm-Folding in Families: A review of Literature and Some New Data
M. Reiss & G. Reiss
Arm-folding refers to the preferential tendency for individuals to fold one fore-arm over the other. This paper reviews the previous literature on family data and twins, and reports new data. In this study about 54% of the population are left-arm-folders, 42% are right-arm-folders, and the remaining 4% reports that they have no preference or are indifferent. Familial data suggest that 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 and hand-clasping. It is possible that arm-folding, as well as hand-clasping and leg-crossing may be an idiosyncrasy due to or influenced by physical bilateral differences in the arms. All family data including mine and others together (arithmetical sum) suggest a genetic basis, although environmental influences are also evident.

Key words: laterality, arm-folding, genetics, determination