There are some bits of history I'd just as soon forget but it's important to remember them. Take eugenics, a word usually associated with the Nazis and 1930s Germany. Eugenics was a "science" that was quite popular in the United States in the late nineteenth and early twentieth centuries. The following is from The Great White Way:

With roots reaching from the mid-1800s, eugenics was an attempt to apply science – in the form of Mendelian genetics – to improve the human race. Using Mendel's pea-plant experiments as a jumping-off point, eugenicists argued that society should consciously work to breed the best genetic traits in its citizens. There were two main approaches: positive eugenics encouraged persons with desirable traits to breed, and negative eugenics barred "undesirables" from breeding.

Though steeped in the kind of racist and anti-immigrant beliefs generally associated with right-wingers, eugenics ideas were at least as likely to be advocated by social radicals and progressive thinkers as by conservatives. Teddy Roosevelt, Franklin Delano Roosevelt, Oliver Wendell Holmes, Jr., Woodrow Wilson, H.G. Wells, Emma Goldman, and Margaret Sanger (the founder of Planned Parenthood) were among its fans. Some, like Sanger and the English critic Havelock Ellis, saw eugenics as a way to liberate women through its promotion of birth control. For those with socialist leanings, eugenics reflected a privileging of society's interests over those of the individual.

Perhaps the most surprising thing about eugenics was its widespread popularity among middle- and upper-class Americans. Popular literature from the late 1800s up through the 1930s was littered with eugenics-inspired language about bettering the human race. Although such language squarely fit progressive ideals at the time, some of the underlying mechanics were downright grisly.

Charles Davenport headed the eugenics movement in the U.S. with the Eugenics Record Office, a group funded largely with Rockefeller and Carnegie dollars. Davenport pushed negative eugenics remedies to prevent births among those deemed genetically undesirable (in order of priority): the "feebleminded," paupers, alcoholics, criminals, epileptics, the insane, the constitutionally weak, people predisposed to specific diseases, deformed persons, and those born deaf, blind, or mute.

Few of these problems could be scientifically tied to genes, of course, but Davenport was seldom troubled by such facts. The "feebleminded" diagnosis alone was so vague and elastic – applying to anyone deemed stupid or immoral – as to be meaningless. Nonetheless, Davenport and his cronies called for segregating, incarcerating, sterilizing and castrating all such persons. (Why castration? Some eugenicists argued that, though sterilization prevented people from breeding, the operation would encourage the unfit to have more and more sex, and spread disease, once reproduction was no longer an issue. Castration, needless to say, solved that.)