I have a friend whose son is a pitcher. He's 5'8", wife is 5'1". He's banking on his son being 6'3"-6'4". I've told him, unless the mailman or milkman is very tall, don't count on it.
When my son was ten he wanted to grow up to play in the NBA. I apologized and told him he was going to grow up to be a 6'2" white kid.