Facts vs Cultural Identity
Thanks to Marc Verstaen for pointing me at this wonderful paper by Dan M. Kahan from Yale.
tldr: when it comes to answering questions on science, people can either tell you what they know, or which social group they belong to, but not simultaneously.
The paper posits that we have two, sometimes conflicting personas:
It is the dual nature of human reasoners as collective-knowledge acquirers and cultural-identity protectors.
Sometimes these two sides conflict. And when they do, people will choose to tell you which social group they belong to, even if they know the facts are not on their side.