Why does the male parent determine the gender of the offspring?
The sperm that fertilizes the egg determines the sex of the resulting zygote: eggs have a single X chromosome, whereas the sperm can have either an X or a Y. The Y chromosome influences the sex of the individual by inducing the somatic cells of the genital ridge to develop into a testis instead of an ovary.
In the process of reproduction, a male’s sperm and a female’s egg each contribute one sex chromosome.
A child’s biological sex (male or female) is determined by the chromosome that the male parent contributes. Males have XY sex chromosomes while females have XX sex chromosomes; the male can contribute the X or Y chromosome, while the female must contribute one of their X chromosomes. A male infant results if the male contributes his Y chromosome while a female infant results if he contributes his X chromosome.