Parashas Tazria
It seems there is an argument between the Torah and science who determines gender. The Torah says the women whereas science says the man. A woman has two X chromosomes whereas the man has an
X and Y chromosomes. He can either contribute an X or Y. Maybe the woman creates an environment which determines what kind of chromosomes he gives. The Harav Ksav Sofer explains the pasuk that as they were afflicted the more males were born. The woman had more desire in the relationship which had more males being born.