I have long believed that people's ages should be measured in more than the phyiscal years they've been alive. I think there are actually various things to take into consideration. Physical maturity is important, but so are emotional, mental, and spiritual maturity, to name a few. The idea that a person over a certain physical age is automatically an adult and under that age is automatically a child, that just seems wrong to me. Of course, there are recognized exceptions to this rule... for special cases. But I don't think the rule should really apply to anyone. Personally, I like to measure my own age in four parts: body, mind, heart, and soul.
Physically, I was born September 21, 1975. Of course, the age of the body is constantly changing.
I feel I've always had a rather adult mind, let's say 40ish in physical terms. Even as a kid. Of course, I guess I was always kinda smart (I think I'm not as smart as I used to be, in alot of ways), but actual amounts of knowledge may change over the years. It's not necessarily about what you know, so much as how you think. Of course, mental age can be confused with emotional age, especially if there's a great disparity between the two, in a given individual, such as myself....
I feel I've always been rather young at heart, and always will be. So my metaphorical heart's age is... I suppose it can fluctuate, could be that of a young child, a teenager, a young adult. Just basically "young" is close enough to its age.
Ah, and finally, my soul. I think it's probably about 4000 years old, a fourth stage soul. If you wanna know what that means, check out my page on soul ages.
Old soul, young heart; that's me. Well, that's about all I can think to say on this subject, for the time being. Hope you've learned something. Maybe you could have fun trying to apply this to yourself, figure out your own ages of heart, mind, and soul... and anything else you can think of....