Yes, the little ones have no idea. From South Pacific: “You’ve got to be taught to hate and to fear. You’ve got to be taught from year to year...You’ve got to be carefully taught.”
Our kids are from China. One unlooked-for but welcome byproduct of an interracial adoption is that you get a rapid education on the surprisingly large number of adoptions that are out there. In such cases, the fact of adoption is obvious, and people make themselves known to you. My wife and I had an inkling, since we both have adopted cousins in our own generation and adopted nephews and nieces, but we are still surprised at how commonplace it is. It's just not much talked about, especially if the adoption is within the parents' racial group and therefore somewhat invisible.
Anyhow, my older daughter, from China, soon found herself in a class of 20 with adopted kids from China, Kazakhstan, Russia, and Africa, and on a soccer team with several more adopted kids, not to mention the two kids from Ecuador down the block. Some of these kids looked like their parents; others didn't. Then add in a number of friends from mixed marriages.
It's not really surprising that my daughter and her friends seem to be oblivious to race. They've grown up with just about every combination you can imagine in their immediate peer group. On my good days, I think the melting pot will do its magic again if we can just find a way to shut down the racial grievance industry that spends all its time nurturing hostility.