Parámetros demográficos y proporción de sexos.

Abstract

in this paper we present the results derived form the analysis of the secondary sex ratio of 502469 births occurred in Catalonia between 1975 abd 1979. This was done by means of a stepwise linear regression, which confronted the variables supposed to affect the sex ratio in man (i.e., parental ages and birth order) whit a dependent variable p, the probability of a male birth. The results showed us that only one of these variables, the age of the mother, could account for a slight percentage of the variation o p (1.64%), while the other two had an almost negligible effect. Besides the differences on sex ratio among populations, a great divergence has been found in the fraction of the variation explained by demographic parameters. Therefore, we wonder if there could be a genetic basis that could explain the differential incidence of these variables on sex ratio.