My husband and I had a conversation just this morning about when to explain race, racism and slavery to our DS4. DS is completely naive about these issues and doesn't think anything of the fact that his friends and teachers are of many different races. I'd like to make that innocence and colorblindness last as long as possible, but my husband made St. Pauli's point:
And, remember, if you don't teach your kids something the way you want them to learn it, they'll probably learn it from someone else if they really want to know.
DS is also such an advanced reader that I've noticed racism and slavery coming up in more and more of the books he's reading. So far, I've sidestepped the issues, but I suppose I'll have to lay things out soon...