Female-biased reproductive strategies in a Hungarian Gypsy population

Hungarian Gypsy populations invest more heavily in daughters than in sons compared to co-resident Hungarians, in conformity with the predictions of the Trivers-Willard hypothesis. These effects are shown for four different measures of parental investment (sex ratio at birth, frequency of abortion, duration of breast-feeding and length of education). Opportunities for hypergamy into the wealthier Hungarian population appears to be one factor causing Gypsies to prefer daughters over sons. We show that differential investment by sex of offspring is directly related to the fitness pay-offs that accrue for each population through both sexes of offspring.