A few days ago I was talking to a friend who has 2 dark skinned mixed-race children who my DS has been around regularly since he was about 6 weeks old and she had asked if he had asked anything about her DD and DS being different because of their skin, when I replied he had'nt she looked quite shocked and said he just does'nt seem to pay attention to his surroundings 
Now there is also a girl at his nursery with an unformed hand which again he does'nt notice, should he be?
I genuinely thought it was a good thing that he has never thought about it enough to ask and just accepts that people are people regardless of colour or disability.
Now my friend has got me worried that he just does'nt pay enough attention and has been oblivious of it rather than just accepting of it.
I hope that makes some sort of sense but it is actually annoying me now as I don't really know anyone I would feel comfortable asking. :)