GENETICS OF NATURAL VARIANTS. IV : HANDEDNESS IN MAN

This paper is a part of study on genetics of handedness in man. We have identified three distinct phenotypes, viz. right-handed, left-handed and ambidextrous individuals, and have opined that handedness is controlled by three autosomal genes, one for right-handedness (H), second for left-handedness (N) and the third for brainedness (D). The two dominant genes interact and H is epistatic to N  thus explaining excessive right handers in the population. Family data based on 370 marriages (1487 offsprings) appear to support the suggested polygenic mode of inheritance. Some possible parental combinations, segregations and statistical presentations are also shown with reasons for not agreeing with all previous workers in this area. Persons with the dominance of left shift, right shift (cerebral hemisphere) and being right-handed, left-handed or ambidextrous have been given probable genotypes. Future studies will indicate extent of applicability of the hypothesis.