Before any citizen enters the role of scientist, medical practitioner, lawyer, epidemiologist, and so on, each and all grow up in a society in which the categories of human differentiation are folk categories that organize perceptions, relations, and behavior. That was true during slavery, during Reconstruction, the eugenics period, the two World Wars, and is no less true today. While every period understandably claims to transcend those categories, medicine, law, and science are profoundly and demonstrably influenced by the embedded folk notions of race and ethnicity.