Baldness is a gender linked (X chromosome recessive trait), like colour blindness.

I am very hirsute and bearded, so I often tell people that it is gravity in action. Everything slid off the top. -)

I knew I didn't have a chance when my mother and both maternal grandparents went bald. Those Rogaine ads with a balding man with a balder father and totally bald paternal grandfather standing behind him are a joke. -)

It is the maternal X chromosome line that determines baldness. Women only go bald if both X chromosomes have the trait, so it should be mom and her father or mother standing behind the balding guy.