these days I reckon about age 4, above that and the clothing fashions try to make the kids look sexy, even DVDs, movies etc are all about this these days
The answer depends on your circumstances and cultures. Some people have to grow up very young and others maybe never do. Legally there are various age thresholds. In some cultures such as Saudi Arabia women are never considered adult and cannot drive cars! You decide! That is the best way anyway!
I agree, I can still get away with it.
Believe me that some people never figure that one out. So you could be 70 and be acting like a kid.