Eugenics is a concept which advocates the manipulation of human reproduction for the purposes of attempting to improve the human species over generations in regards to hereditary features. It was first put forth in the late 19th century by Sir Francis Galton, and was popular in scientific and political circles in Europe and the USA during the first decades of the twentieth century. After it was used to justify the racial policies and atrocities of Nazi Germany, though, it was almost universally reviled. Modern inquiries into the potential use of genetic engineering have led to an increased invocation of the history of eugenics in the discourse of bioethics, usually as a cautionary tale.
See also: The Kallikak Family
Madison Grant's map of the races of Europe, 1916.