Late to the party, but I was just talking about my grand-nephew on another thread. He was most curious this weekend about not only baldness among his elders, but also why different people have different patterns. He wanted to see a picture of my brother with hair, but he's been mostly bald since his late 20's, so doesn't believe that young skinny guy is the same person!
They live in New York without family nearby, so no close contact with older people on a regular basis.
He was also having a great time studying hair color and texture - in his mind, couples should have similar hair, so he was concerned why Uncle's hair was curly & gray, while mine brown/blond and straight, etc. So much fun to watch the wheels turn.