Questions about the causes of similarities and differences among individuals, and on the interaction between innate and acquired characteristics, have probably been asked by all peoples at all times in human history. Genetic research attempts to provide scientific answers to these questions. Although many genetic researchers investigate these questions solely for the purpose of gaining understanding, other scientists and social activists hope that genetic research will produce understanding and technology for the purpose of improving human biological, ecological, and social conditions. Arguments about the relative importance of nature and nurture have persisted in the intellectual history of Western civilization, but these arguments provoked little censorship until the mid-nineteenth century, following the publication of Charles Darwin’s controversial evolutionary theory on the origin of differences in species. Societal censorship of genetic research intensified during the twentieth century, when powerful genetics tools became available to scientists trained to formulate hypotheses and produce data that can influence social policy.