I was thinking about this some more today and remembered there are a few people in my life (as in family & friends) that I'm not affectionate with and that list is really short.
1. I can't remember when I was willingly affectionate with my father. I did give him hugs and stuff but it always felt awkward to me even when I was around 8 or so. I just didn't feel very close to him at all, and still don't. As I've given both of my folks the cut direct, neither of them get hugs so at least I don't have to worry about that anymore!
2. FIL. Now I adore my FIL. He's got this very dry and bizarre sense of humor that he passed on to DH. Lots of bad but still somehow hilarious puns. So my awkwardness in hugging the man has very little to do with how I feel for the man. I think in his case it's that he himself is not really much of a hugger. If you give him one he'll return it, but I don't see him really seeking people out to hug them.
I have a very affectionate extended family. On my dad's side, my grandparents were both VERY affectionate. Grandpa was kind of a close talker and there was no such thing as a quick hug with that man. Nor with his son and namesake, my Uncle "Patrick". Or with Patrick's son either, for that matter. Uncle Patrick, my late Aunt Jo, and their two boys are a very, very affectionate family in words and gestures.
I usually don't hug people when I'm first meeting them, though when I first met my best friend, we'd already been talking for about a year and a half by that point so when I went to see her we both hugged when we first met face to face.