Can culture shock occur in one's own country of birth ?

So I attended my first customer dinner that our company hosted over the last weekend.

It was at hotel facing the ocean, the views were perfect, the food very good, the presentations went off great, our team had a good time, I gave a reasonably good little spiel at the end of the presentations (public speaking is not my forte but I think I'm getting pretty good as I seem to be always presenting stuff to staff and clients)

They were a big client who have been with us for over 2 years and have various textile factories in the island (they make stuff for Banana Republic). Most of the people working there were Muslims and we had made sure the food was halal (not sure of correct use of the term) and that alcohol was alright to be served etc.. They were all lovely and friendly and we were getting along great, then a gentleman walked in a few minutes late and he was introduced to my dad and I by the head honcho, and when he came out to me, I held out my hand to greet him and he refused to take my hand ! I was shocked and a little embarrassed but since he shook his head from side to side and smiled at me I let it go. At the end of the night my dad leans over and says “Oh I forgot to tell you, if they have a long beard and they have shaved the top part of their moustache, they are really orthodox and don’t touch women.” Thanks Pa, you're a gem !

I grew up in Sri Lanka, but I don’t remember being so culturally aware or it would seem I haven’t been intergrated into society. My school mates were a mixed bunch (or so I thought) but since I schooled at a private English school maybe the cross-section of the people I hung out with weren’t your average Joe or well Sarath (refer Sunlight advertisement in the early years featuring the line “Aney mangthe Sarath”) Or maybe one’s grasp of social etiquette when young is non-existent.. Whatever the reason, it would seem I have ended up becoming some kind of socially in-adept freak ! Alright the last bit was the drama-queen in me.. I'm sure I'm not that bad.. But I do at times feel a little out of place here.

Oh dear, I have much to learn..