What is it with boys and their penises?

My son has taken to pulling down his diaper just enough to check and make sure its there at every opportunity he has. If he his going diaperless say before or after or during a bath its pretty much all he looks at. Its really amusing actually to watch him bend over as far as he can to get a good eye view. Its even funnier to watch him walk into walls and things because he is too busy checking out his peter.