Ok, minefield here, but 'black' isn't a genome. In fact, Africa, cradle of all humanity, has more genetic diversity even today than the rest of the world.

If one were to evaluate that hypothesis, the data from Switzerland would probably not be particularly helpful and may be potentially misleading because it is a small sample size, and as you may know Switzerland is particularly judicious in who it allows to immigrate which one would imagine results in a skewing of the general population dynamics.