Boys and girls

Reading Chillsider's post reminds me that I am to be grandmother to another boy. That will be three grandsons. Wow! Costa, my son, says his father-in-law is chuffed because it proves a theory he has about hairlines and how the hair-line of the preceding child predicts the sex of the next. the sex of the first child is predicted by the mother's hairline - whether it's pointy or straight. I can't remember which means what.