It seems a lot less than it used to be a few years ago but I can't pin down exactly where.
My father who is in his 60s has a lot more hair than me, especially around the temples.
I have the least hair out of anyone in my family, actually.
http://i.imgur.com/Halym.png
Late 20s. Never noticed it until the past couple of years.
Thinking of starting fina, just trying to weigh the risk/rewards.