Well, there's sort of a common idea of Culture -- music, food, art, traditions -- and then there's a broader definition of culture -- basically that the culture you're raised in defines your norms and attitutudes.  It's very difficult to know your own culture sometimes, especially in the isolated ones.  

You were raised in a part of So Cal that I was shocked to find out even existed the one and only time I visited there.  I was raised in a rather dubious part of Long Beach -- geographically not far.  Socially and economically, very different I'd imagine.

Yet, we probably have more culturally in common than we do different.  I'd wager good money we share these:

*A natural tendency to have a large "personal space" boundary -- larger than is required in most parts of Europe.  I believe most Americans have this, but maybe not on the east coast cities.  All the westerners, definitely.  It's one of the first things I've noticed travelling or meeting people from other countries -- they get too close!  It's actually never really bothered me, but says something that I've been aware of it.  I've seen several Americans get uneasy, taking it as a sign of aggression.

*Almost everyone we know from "home" learned how to swim at a very young age.

*We know how to pronounce Spanish words.

*We could probably happily talk for ages about traffic the way other cultures talk about the weather.  Where I currently live, I still try to engage people in discussion of the pros and cons of freeway vs. surface street from point A to B, but their eyes glaze over.

*Our default "normal" distance is 20 minutes.  By car.  Anything different is "close" and "far."  This is probably changing for you now you've moved, as it has for me, but I still slip back to it on visits.  I've also noticed that "20 minutes" is a very fluid notion in LA -- it means it could be done under optimal conditions.  It doesn't account for traffic.  We all know this, but it confuses tourists.

This is, of course, the tip of the iceberg and just what popped into my head.  

Maybe we can eventually make language a complete impediment to understanding. -Hobbes