Why do some men have no hair on their limbs?

My dad is in his 50s, and he has NO hair on his legs at all. He still has all the hair on his head, however. I don't consider myself a very hairy person, but I definitely have hair on my limbs. I think one of his doctors had thought it was a sign of diabetes and poor circulation in the legs. Is this possible, or is it more of a hormonal/hereditary/age thing?