female hair loss age 55...help?

My hair has never been my crowning glory..but a few months ago someone said, "do you realize your hair is getting really thin??"..I hadn't really realized it--but now it has gotten much worse and I don't understand what it is about. My parents had their hair and their scalps did not show. Any ideas about what I should do? My scalp shows alot right behind the area where one has bangs.
any help on this?