Aspergers and Me explains why she often does not like being touched:
Touch is sticky!
That’s honestly the best way I have to conceptualize it. When someone touches me, that touch sticks to me. It stays there, being all weird on my skin, and I have to rub it off. Or scratch it off. Or claw it off. It varies. Everyone’s touch is sticky, there are no exceptions. So for me, being ok with someone touching me is about being ok with their touch sticking to me. Actively touching someone else is like saying “hey, I like the way your touch sticks to me.” A hug involves getting someone’s sticky on me in places I cannot easily rub it off. Not without doing that whole bear-scratching-its-back-against-a-tree-move, anyway. CLASSY. So if I actively hug you, I’m saying “your touch is going to stick to me in weird places for probably quite a while, and I’m good with that!”