Some roles start out with the character not in the teens. How about a flaw that tacks on the equivalent of 15 years (race specific), that way a human wouldn't start at 15 but 30 instead. Or an elf wouldn't be 80 and would be 130 years old. I have no idea what the ratio of years to race is but you get the idea.

I requested this from Santa Zulg in 2008 and it got circular filed, fwiw.

I'd say the price should be that your initial stats don't get the benefit of aging, but do get the drawbacks.

Otherwise this could actually be an advantage, since it would boost useful stats right from the outset.

Wanted to do a human thief that started at 45 after he ditched his family.