This is not always true, however, as in the case of priests, teachers, and parents. At least four people you know will join the armed services. Three of those people will quit and the fourth person will wish they had. Upper level math turns out to only be good for passing upper level math tests. You won't grow a mustache as soon as you're able.
Facial hair comes in spurts and it's almost never symmetrical.
It's also never the color you think it will be. Your skin will not magically clear up upon turning a certain age. Even if you think you've reached that age, you haven't. Look closely at grandma's face. You'll never forget the moments in life where you've really hurt someone's feelings, but they might so never bring it up.