Sad but true. Margaret Sanger (US) was one of the biggest promoters of eugenics in the early part of the XXth century. Nevertheless, I believe in certain rare cases humans should be sterilized, unless they wake the fuck up and see reason--like NOT giving their kids names that will get their asses kicked on a daily basis.
Oh, and it turns out Hitler and Stalin are pussies compared to the death toll for good ol' Chairman Mao. 600 million, at last count.