Evidencia de componentes genéticos y ambientales en la lateralización manual. Estudio en 120 familias mexicanas

Environmental factors as well as different modes of inheritance has been suggested to explain the etiology of left-handedness. In order to improve knowledge of this problem, manual skill (MS) of parents (n = 234), siblings (n = 506) and children (n = 126) of 60 right-handed (RHI) and 60 left-handed (LHI) index cases (IC), born in Mexico City, were studied. Parents and siblings of both IC had similar frequencies of left-handedness. Quite the contrary, 36.7% of children of LHI were left-handed, while 7.3% children of RHI happen to be left-handed (P < 0.00025). No differences were found in the appearance of perinatal environmental factors. These findings are explained in part according to the pressure exerted by parents and/or teachers for dextrality. The impact of this influence modifies the effect of several unknown genes (multifactorial inheritance). The understanding of the above mechanisms in the etiology of MS is relevant not only for academic purposes, but for the educational sphere as well.