This is one of those pieces of "Hidden History" that is known but rarely taught. My family had personal experience with it back in the 1930s in West Virginia so I know about it but it is generally glossed over or not mentioned at all in class room history books.
Eugenics was a very popular and respectable movement during the late 1800 to the early 1900. If you want to really churn your stomach you can read about the "Family Fairs" held in the 1920s. The ideals of Nazi Germany were born in the "Progressive Policy's" of the US Democrat Party.
People were just animals and should be bred and improved. The "impure" lines should be cut off.
This included people who were poor, people who had skin darker then a paper bag, people who didn't speak English or didn't speak it "properly", people who were unemployed, women who were raped, children who had birthmarks, children who had cleft pallets (cat mouth), ears that stuck out... In fact a good portion of the human race.
By their lights this was ok, after all they weren't really "people" and had no rights as a person.
If you like I can refer you to some websites.
I would like to educate myself by looking at those web sites.