Understanding and updating beliefs on deeply engrained topics can take enormous efforts, but sometimes it can be so hard that the listener cannot even in principle accept the new reality. The listener is simply not ready, he lacks a vast background of reasoning leading to the new understanding.
What fact that you know is true but most people aren't ready to accept it?
By "you know is true" I really mean "you are very confident to be true".
Feel free to use a dummy account.
https://www.youtube.com/watch?v=YL6D3iNlt6I (short)
https://www.youtube.com/watch?v=4UoFjme1Sec (long; crappy ai summary - hit expand to see the individual (janky) summaries)
Have a couple of videos that go over a related concept - racialization is a false, noncausal correlation that generates correlations by nature of people assuming its structure. If you look more closely, you find a wide variety of features, some of which become correlated through prejudices. It'll be interesting to see if that applies to genetics; the racelessness activists I know all insist that there's negligible variation in iq from genetics, whereas I'd insist that variation in iq is definitionally a disease to be treated, and that within-lifetime genetic interventions are a major focus we need to have with transhumanism.