“Classification is real, but it is based much more on a set of social definitions than on genetic distinctions. Legally defined categories for race differ from one country to another, and they change over time depending largely on the social and political realities of a particular society or nation. The notion of discrete racial categories arose mostly as an artifact of centuries-long immigration history coupled with overriding worldviews that white superiority was inherent, a purported genetic destiny that has no basis in modern science.”