I have always had a problem with touch - so much so that in uni my friends developed a "bubble hug", which involved running up to me and reaching out to mime hugging my personal space bubble. I was fortunate to have friends who respected it and joked about it in a pleasant and not demeaning way.
My mother is a cuddler and apparently I was a great disappointment as a child. Even as a toddler I would pull away from her, and I would jerk my hand out of hers and exclaim, "YUCKY!"
I am very physically sensitive to another person's touch, particularly on my bare skin, and especially if the touch isn't pressured. If someone lightly and briefly put their hand on my forearm, for instance, I could feel an imprint of their hand mark burning and tingling on my skin for up to an hour afterwards. It felt as though there was a chemical reaction, like acid, on the surface of my skin. Thankfully this sensation has diminished somewhat, though I still feel a bit of a prickle afterwards.
My behaviour has also gotten a little better with age - mostly because I recognise that it is very rude not to reciprocate physical contact (hugs, etc) and, no longer being a kid, I can't get away with it anymore. I just don't see the reason for unnecessary physical contact: I'm actually okay with shaking hands, because it's firm, perfunctory pressure, and even proper massages when there is a point (muscle tension relief). But hugs? Who on earth needs a hug? I just don't get it. Also, holding hands? What on earth is the point in that?!? I also despise that weird strokey touch that so many people do - especially couples. Not only do I not like doing it myself but I feel slightly sick if I'm in the same room as people who are touching. I just do not understand why people touch each other when there is no distinct purpose to it.
I get very odd looks when I try to describe my feelings about such things, so lately I've tried to skirt around the issue. It can get very complex with "romantic" stuff - try explaining to a guy that you fancy him and would like to have sex with him, but apart from that, could he please never touch you? ...Yeah. This is a situation I'm going to have to deal with pretty shortly, and I'm dreading it.