Final answer:
Eugenics started in England, but had a significant following in the United States, where forced sterilization policies targeted marginalized groups. Supported by prominent organizations and influenced by racism and pseudo-science, these practices influenced Nazi Germany's eugenics programs which eventually discredited the movement.
Step-by-step explanation:
Eugenics had its start in England but gained a significant following in the United States during the early 20th century. In the US, the movement was characterized by policies of forced sterilization, which targeted tens of thousands of individuals from various marginalized groups, including but not limited to people of color, immigrants, and the mentally ill. These policies drew not only on racist and xenophobic sentiments but also on pseudo-scientific principles that claimed to improve the human race through selective breeding. Nevertheless, it was the extensive eugenics program of Nazi Germany in the 1930s and 40s, which led to the forced sterilization and killing of hundreds of thousands of individuals, that ultimately discredited the movement globally.
In the US, advocates of eugenics had financial backing from prominent organizations like the Carnegie and Rockefeller foundations and received support from scientists, public health advocates, and politicians. The eugenics movement erroneously posited the inherited nature of traits such as poverty, criminality, and mental illness, and proposed radical interventions, including eugenicide and forced sterilizations, to prevent the reproduction of those deemed 'unfit'. American eugenics practices influenced those of Nazi Germany, whose brutal policies during World War II prompted a worldwide reevaluation of eugenics as a whole.