I'm with Wolfgang, beware of people quoting "science". They may not be as reasonable as they seem. We may all have 99.9999% of the same genes, but it is a fact of life that the average inhabitants of, say, Iceland and Zimbabwe are superficially very different in appearance. And (a) these differences are undoubtedly genetically determined and (b) human beings have a sad and undistinguished history of acting very unpleasantly because of these differences.