Tart might be a but much... What happened was, there's this boy in my science that have no feelings for - I can assure you of that. But today, he sat by me at break, and we were very close - closer than me and my best friend sit. He didn't sit on my lap (I'd probably laugh if he did), but our legs were touching, and so were our shoulders. But I sort of liked it. But then I realized that I like it if any boy touches me or comes close to me. Obviously not any boy; not ugly ones. But also I like it when attractive girls do also, but more so boys. I don't get anything from it; it's just that I like it and fund it really nice. But what does that mean, it can't be natural? I have to admit, the boy was looking very nice today - we could go in our own clothes - but still, why? He always gets quite touchy with me in lessons, but I'm not taking that as anything. And if he did mean something by it, I'd have to respectfully decline. So erm... I am a tart (that word makes me laugh)?
Why on earth wouldn't it be natural? And a more pertinent question is, why do you care if its natural or not?
Shoulders are an erogenous zone, that's probably why. Alternatively, since you seem to be a bit unhappy at the moment, you might just be appreciative of the human contact.
The problem is that other boys don't like contact with other random girls or boys - depending on their orientation.