For example [vaguely]: writer creates a character who behaves like X, despite nobody actually behaving like X in real life. Then characters behaving like X become a wide-ranging trope. People in the real world begin to think it’s normal to behave like X, and subsequently start actually behaving like X themselves.
Any actual examples of this phenomenon happening?
Sorry, but I’m also old enough to remember the world before wide-spread use of the internet and anal sex was popular already then.