Dominance of one cerebral hemisphere in man. A survey study based on handedness and its pattern of inheritance in a sample of Iraqis

ABSTRACT

A survey was conducted in four high schools in westen Iraq, in which each student was asked to report on the handedness of his parents, his brothers and sisters, and himself. The size of the sample reached 10,000 individuals. The percentage of the right and left hand users in the group as a whole were 93.7% and 6.3% respectively. Comparing male and female right-handedness, the number of females was higher than males by 1.5%. To trace heredity of the trait, the Chi-square test for association and the conditional probabilities were calculated. They proved the following 1. significant association and interaction exist between the characteristics of parents and those of their children. 2- cerebral dominance for handedness is heritable as reflected by the heredity of the trait, which follows clear interaction patterns