In the interest of being both fair and also SO balanced; Liberals have almost just as bad of a track record with issues like autism. As a lefty, I used to get into outright verbal brawls with people that were full out spouting eugenics and either didn't realize it, or didn't think it was technically problematic in this specific case. The whole 'I don't vaccinate my kids against deadly illnesses because it can cause autism crowd,' who are outright saying the child is better off dead than autistic.
MOST of that attitude seems to have come out of the liberal new age Whole Foods soccer mom crowd. Liberals were absolutely fucking terrible for spreading around bad science and eugenics as a fun hobby for many years. And it's still one of the most effective liberal-to-conservative pipelines, particularly for women, in my view.