Cultural differences can make you crazy. I sometimes close my eyes and repeat, this person isn't really trying to insult me, he is just from a different culture. There are so many it can drive you crazy. Never show the bottom of your feet to an Arab. Never eat with your left hand in many cultures (that hand is for taking care of bodily functions). Never, ever spear food with your chop stick. When you meet someone new, always show both of your hands. I grew up with a myriad of different cultures, and as I get older, find myself with many more.
Many Middle Eastern men, Christian, Jew, or Muslim, will hug and walk arm in arm with their male buddies (and not gay), but would never, ever show that much affection to their wives, female friends, or daughters.
There are so many cultural differences that you could fill a book.