I should start by saying that this post is about people of the same sex hugging/kissing each other to show intimacy, affection, warmth and good cheer in a non-romantic manner.
I am not fond of hugging people I am not close to. As a kid, my parents would insist that I kiss the old and the elderly in my extended family. I hated going up to the old person in question( typically someone I did not know), smelling the combination of odours of their sweat, hair and medication and then kissing the tired skin of their cheeks. As I grew up, my parents stopped insisting upon this and boy, was I so glad. Recently, I was telling my mother this and she has no recollection, none at all, of any such insistence on her or my father's part (eey, enikku ormaye illa = I don't recollect at all)
In Kerala, I am yet to see people hugging their friends in the casual way it is done up north or in the West. When offered a hug by not-so-close friends, I have always accepted it as it would be rude to reject a person offering up their body to you to touch. But I have never felt comfortable.
It really came to me one day in Delhi. A friend and I were at her sister's house for tea. I was introduced to the sister's mother-in-law. When we were leaving the lady in question hugged my friend and then me after saying, "take care, beta, all the best". I am sure she meant well. I had just moved to Delhi and I was looking for a place to stay. I was staying for a short while with this friend until I found my own apartment and this had come up in the conversation. But the hug left me feeling invaded.
In Delhi I noticed colleagues (even the ones who hated each other!) hugging each other. I think there is a North-South divide or to be more specific, a Punjabi-Malayali divide in this.
How much of this opening up our bodies business is related to caste and how much of this is related to space/privacy? On the latter, I should say that we Keralites are not a particularly space/privacy conscious people. I think some of the answers may lie in caste. In her excellent book "Unknown Turf", while writing about caste in Punjab, Annie Zaidi points out that caste in Punjab has never been about purity-pollution. Remember that in Kerala we all practised untouchability until quite recently. The ritual purity business is not widely practised now, but it manifests itself in our refusal to open up our bodies to others, including to being hugged. This is only a tenative conclusion, btw.