A white and black marry and the child will be MIXED race. So you are wrong. Next question? Like I said, you just demonstrated that race is politicial.
I'm not sure that it is helpful to characterize race as just "political". The many genetically determined characteristics which constitute "race" are real and have required many centuries to come about. That there are consequences to this effect should not be a surprise and calling them all "political" perhaps understates the challenge.
One poster pointed out the association of particular diseases with a single race. It may require politics to address the issue, but the issue is not of political origin. I would not term as political the forces in the past which led to the isolation and differentiation that we observe.
You are certainly correct that the offspring of people of different races are of mixed-race and not of a presumed inferior race. You responded probably with less derision than I might have.