Maybe tribe is the best word for it. The people you spend your time around. I forget sometimes that people outside my tribe do not understand my 'inside joke' humor always.
But if you look at culture in the way that most people define it, I find it mostly geographically based what kind of culture we live in. And that gets challenging when you are moving around a lot like me ;)
The dominant culture is quiet similar everywhere, rather herd like, but exhibiting different features base do on those who lead the herd. They misinterpret the words of thinkers and artists who were not part of the herd and ar influence s by those misinterpretations. I find artists and those truly connected to nature to be quite similar everywhere as well and I can relate to them much easier than the herd.