The way in which we interact as human beings can be absolutely fascinating, but there are huge differences in various parts of the world, which does then lead to a certain sense of confusion. Take the concept of non-contact and high-contact cultures. Perhaps you are not even sure as to what they entail, but a quick explanation will certainly suffice.
Basically, it refers to different cultures where there are varying degrees of personal contact, as in some places it is seen as being far more prominent and allowed than it is in other places. Ultimately, it can lead to you freaking out if you are used to virtually no contact and then encounter people that feel as if they are touching you on a constant basis.
Generally speaking, Northern Europe and the Far East are rarely interested in the contact part of socialization, but the complete opposite is true in Latin America, Southern Europe and the Middle East. In those cultures, it is certainly more full-on, but of course it is always in a friendly manner at all times.
So, if you travel to any of those cultures that are the opposite to what you are used to, just remember that different cultures do act in various ways and that it is nothing personal.