Eugenics came out of biology. For a a scientist you just missed the obvious.
No it didn't, it came out of prejudice, and prejudicial people attempting to fit science to their prejudices. One of the notions that began Eugenics was that the undesirables were going to overtake the desirables with their higher birth rates, and that population needed to be controlled to avoid reduced fitness from the higher proportion of progeny from the undesirables. The Nazi's took it even farther with their pure race madness. There is no biology that supports this flawed view.