If you don't want everyone to know something you do. It's probably because you are ashamed. You should stop that then. If it's because if "societal norms" then fuck that. Be yourself in the face of that shit society, and you will feel much better, and find better friends that like you as you are.
There are plenty of things that I'm not ashamed of, that would be embarrassing to have a relative see. I'm not ashamed to take a shit rn but I don't want my relatives to see me doing it. All humans need some degree of privacy.
I am all for poking at this viewpoint, I'm not sure it's actually universial myself. But taking a shit is just not embarrassing, I don't think it's a good example. Yeah, privacy definitely matters, but what I'm getting at is, if you do stuff alone that makes you ashamed, it's just not healthy imo