I'm 18 and I keep doing my best to remember what it was like in middleschool and elementary school. The mindsets and lessons are so very different that it's excruciatingly easy to forget.

Children in middleschool often just don't know. They don't know what's going on on the outside and they don't know what's going on on the inside. They struggle desperately to understand and emulate the adults that seem so sure and just do things. So if it might be normal that some people cut, then they would pick that up to seem more normal. Or if it seems interesting in some strange way, they certainly don't want to be boring, they want to adapt aspects that will make others interested. So having some sort of rare trait would boost other's interests.

At least, that's what I think is going on.