As I've mentioned before, I am not and never have been a parent, so most people don't think my opinion on parenting matters counts for much, but I've always felt that it's important that kids believe this from an early age. It's not entirely a myth, because in an ideal world, it could be true. Since we don't live in an ideal world, most of the time it isn't actually possible for kids to grow up to be anything they want to be, but if they don't believe it they won't try to be anything at all. A little hope goes a long way.