It's probably one that's embedded into many. If you boil it all down, what does everyone do that's the same?
Maybe it doesn't reflect very well on me
... but one of the first differences I noticed in getting to know Islamic culture is how males and females relate to one another. Even if there are some naughty Muslims out there, everyone knows pretty much how it's supposed to work, I think. Rulesand values surrounding gender relations are a pretty big part of any culture.