I've had to share my room with my younger sister for most of my childhood and teenage years. And even when I had the room to myself, the door didn't have a lock or anything to prevent any member of my family just walking in like it's none of my business.

It didn't help that for some reason one of the wardrobes with clothing was in the same room. Like, not just my own clothing, but my parents' and some bathroom towels, I think. So I didn't even have a good reason to not let my parents walk in since they might have needed something from the wardrobe. (That is, of course, assuming they'd even listen to reason.)

Personal space is such a weird concept to me, still. I might now be overcompensating for my cramped teenage years by willingly self-isolating. And I don't really know how to comfort other people other than giving them space, because that's what I was lacking the most.