“It’s not like political correctness creeped in to genetics recently.”
Mendel and Darwin were roughly contemporaries. Darwin certainly believed in the inferiority of some races. While some of his “races” are ethnicities by our standards, some were races then and now. I don’t know the views of Mendel.
Back then scientists could advance theories, however reprehensible, without risking their careers. The bad theories would be banished when better evidence was discovered rather than via ad hominem attacks.