In early twentieth-century America, the novel technology called “eugenics”—a potent hybrid of biological science, statistical method, and cultural assumptions—won a diverse following of academics, animal breeders, social workers, criminologists, psychiatrists, institutional superintendents, philanthropists, and activists spanning the political spectrum from socialists to white supremacists. Although heirs to the Enlightenment pursuits of science, reason, and a rationally organized state, eugenicists rejected the Enlightenment's egalitarian strain, insisting that hereditary endowment determined social structure. Fusing Darwin's theory of evolution and Mendel's discoveries in plant heredity, eugenicists claimed to find distinct genetic roots for the many problems of personality and society that alarmed their contemporaries: from “feeble-mindedness” and “psychopathy” to “delinquency” and “hypersexuality.” Within the bright lines of a eugenic worldview, the poverty and crime that pervaded an avowedly meritocratic urban-industrial democracy were comprehended as the offspring of hereditary “mental defects,” racial “mongrelization,” and sentimental charitable efforts that, in a vain attempt to reform deviant individuals, had only assured their survival and reproduction.