We can be convinced that literally anything is "normal." We're social animals and we live in a socially-constructed reality. It's more important to our individual survival to agree with the group delusion than to be objectively correct. In the 80s and 90s it felt like people had started living in a reality constructed by TV commercials; if people didn't do it in a TV commercial it was weird, and if people did it on TV then it was normal. I guess we probably get our cues elsewhere now but clearly we don't get them from our evolutionary social sources and there is a lot of reality hacking going on.