US was fully onboard with eugenics leading up to WWII. There's a whole lotta retconning going on.
Not the least of it is that US were the heroes in WWII. We were "neutral" until the thing was half through, and even then barely even fought the Germans. History props America up, because one of our biggest exports is "history"...but we're the third-stringers who soaked up the glory when we finished the game 30 points up...while we were brought in with a couple minutes left and up by 50.
Us milennials are the worst of it. We got taught by boomer history teachers who heard endless exaggerated war stories from their dads and uncles and had that to feed their already stubborn attitudes. Or worse, Vietnam vets.