My parents have such a bias towards their and their ancestor’s culture/religion, that anything said in favor of it will be believed instantly, and anything critical of it will be met with hostility.
I do not dare point out to them basic falsifiable truths about things such as medicine (e.g. this simple action will cure cancer or reverse male pattern baldness).
My parents are very gullible people. Skeptical about exactly the wrong things, repeatedly wrong year after year, yet ever so trusting of the same bullshit sources and rhetoric, as long as it resonates with their prime belief about the superiority of their culture/religion.
I see this in mainstream US too, with the antivaxxers who got a C in high school biological or 5G crazies who couldn’t pass a physics class.
Once someone has formed an identity around some core assumptions of the world, anything that challenges it will be seen as an attack on one’s ego.