I'm not suggesting darwinism here, just availability of information. Assuming information or communication is not being actively suppressed (e.g. the Great Firewall), then it's up to individuals what culture(s) and traditions they want to uphold.
Social pressure and influence. I could feel myself changing when moving between Norway and Germany. I have the same amount of information, but I involuntarily adjust to my environment. I don't like everything about Norwegian culture (it makes your life a bit boring), but I like a lot of it.
