Eugenics was very popular among Progressives across western Europe as well as the US. Compulsive sterilization, certification of marriages to avoid unwanted breeding of undesirably character or deformity and worse were considered "the science" of the time, and a moral virtue among a fair few Christian sects as well. Fundamentalists and Catholics were among the few religious groups in the US who opposed it, and were ridiculed as ignorant.

The evils perpetrated in the death camps and elsewhere were nothing more than the logical end conclusion of eugenics in general.