It is quite simple.
I blame racism on race.
Get rid of all race.

We'll all be the same.
One big happy family.
All the same color.

Another option is nanobots that permeate skin and bend light so that we are all invisible and can't see each other. We can only find each other by smell. We could walk around naked. There would be no more "fashion" or even rich or poor and everyone would have sex with random partners because, hey, we would all be invisible anyway.