Why am I so brown?

In a cab, on our way home, J asked me "Mummy, why crocodiles comes in so many colors? Some are grey, some are black and some are green."

I said, "Just like humans, J. Some are dark, some are tan and some are fair."

J said "Do you know why I am so brown, mummy?"

Secretly hoping that he will say something like "That's because I am like you" so I said, "Mmm...no i don't, J. I don't know why you are so "brown"."

J said "That's because I drink a lot of Milo, silly Mum!"

At that point, even the taxi driver burst out laughing.