I believe anyone who spends long periods sitting in one place is more likely to father a daughter than a son. The theory is that 'female' sperm are more resilient than 'male' sperm, so are more able to survive the overheating of the testes caused by such inaction. The phenomenon is also apparent in long-distance lorry drivers.
A straw poll among my Squadron colleagues a couple of years ago revealed about two-thirds of children to be daughters.