You mistake fashions for scientific findings. The Nazi effort to exterminate the the most superior race on earth made many people want to believe that there are no inferior people and and no inferior races. This has been called "Hitler's revenge."You've already been dismissed.
Except it isn't science, is it? Most of this Eugenics garbage was rejected in the 1950's (Too late to prevent some truly awful applications.)
The problem with any "Science" that proves Group X is inferior to Group Y, is almost always advocated by Group Y needing to feel better about itself.