To remove certain genetic diseases → we have to remove heterozygous gene carriers → population vulnerable to certain plagues (reminder: it was Mendel *not* the Darwinists/Eugenicists that established the laws of genetics)

1st Internat. Eugenics Congress: presided by Charles Darwin’s son (L. Darwin) dominated by Darwin’s cousin (Galton). Eugenics was Darwinian family business. In his final address, Darwin’s son presented eugenics as “the practical application of the principle of evolution”.
The laws of Genetics were discovered by a monk (Mendel) using something rare for Darwinists: math & method. Darwin had ignored or missed Mendels’ work. Now some claim he was a fellow “Darwinist” because he had read the Origins & used Darwinian vocabulary like… “element”.

Mendel taught Math & Greek to an elementary school in Brünn. Proficiency in these subjects had qualified him as a priest at a young age (Augustinian community). He initially failed his exams at the University of Vienna. His lowest marks were scored in… biology & geology.
A moral judgment often implies “I’m better than you”. The anti-theist atheist (Darwinian) moral judgment implies “I’m more evolved than you”. Eugenics is rooted in a progressive ideal of a pure human type, free of weakness & superstition (e.g. religion).

Once again, Darwinism offers the *minimum* possible tools to discover something meaningful (e.g. genetics) and interprets any discovery in the *maximum* in favor of Darwinian validity (a posteriori, after genetics or DNA is appreciated, now considered “proof” for Darwinism).
Eugenics was not *just* a science. It was all sciences combined. Every BS scientific domain pretends to be “over” the other domains by creating a composite (complex) combination of them all. Logo from the 2nd International Eugenics Congress, 1921

Auguste Comte who coined the word “sociologie” had done something similar. The “degree of complexity” (complexity science) naturally puts the new BS domain on top of a hierarchy of sciences (here sociology on top). Also notice a similar devaluation of math (again at the bottom)
