Note, this all started around the same time the Nazis came to power in Europe.
I saw something on the history channel how this was practiced by the Nazis.
No, it started before, in the teens and twenties, and inspired the Nazis to some extent, who then took it to an industrial scale to the point of killing those deemed undesirable outright.
State eugenics boards were fairly common as were state-ordered sterilizations. It was regarded as a progressive, enlightened thing at the time, but is painted as being anything but now. The progressives have now progressed to just killing them in the womb, and are horrified at the actions of their ideological predecessors, feigned by the knowledgable among them, genuine among the naive.
It started before the Nazis. The Germans adopted it about the same time as most everyone other civilized country. It was very in vogue as a science right then. It still exists, but no longer as a unified science.
There are two sides to Eugenics. The first is the elimination from the human genetic pool of serious defects, which is a very attractive idea to the medical community, because they are the ones who have to deal with the human casualties and suffering caused by bad genes.
For example, the last recent effort at wiping out bad genes was not done through sterilization, but by homicide, in France. Hemophilia, the “bleeding disease”, is genetic, and expensive, requiring human blood clotting factor injections. So quite consciously, the head of the French medical authority exempted HIV screening from the preparation of human blood clotting factor injections.
This ended up killing the vast majority of the hemophiliacs in France with AIDS. France is now hemophilia free. The man responsible was sent to prison, but he considered his actions “worth it”, to rid France of that disease.
The problem with such efforts is that they are very prone to corruption. In the US, “sterilization courts” were instantly corrupted, both sterilizing poor people with no real political representation, with an emphasis on, but not limited to black people; while those who were textbook examples of people who needed to be sterilized by the rules, but whose families had wealth and influence, would be free to keep and use their fertility.
The most extreme examples of this form of Eugenics are found in socialist and national socialist genocidal schemes, one of the more recent by Paul R. Ehrlich, whose “The Population Bomb” was an earlier version of Man Made Global Warming. He wanted to sterilize most of the people in the world, hoping to do so by contaminating food and water. He “conscientiously” decided against this idea, because it could harm farm animals, which he liked.
The other side of Eugenics is much less well known. It is the selective breeding of people to produce better people, howsoever that is defined.
One of its most successful examples was not based on science so much as by the good guesses of the leader of an idealistic commune of northwest European immigrants in western New York State in the 1840’s. By distancing marriage and reproduction, he was able to breed several dozen American leaders in diverse fields before his commune disintegrated.
They were fortunate in that they had also quickly reached the saturation point for inbreeding, resulting in a bunch of bad recessive traits coming out, if they had continued.
More recently, the Chinese have attempted selective breeding among their elite classes, but this is not doing well, as their genetic pool is too small, and genetics is far from being understood well enough to intentionally breed for intelligence, strength or health, without guessing.