This kind of thing happens with language too. Areas which historically had a lot of immigration sometimes end up with immigrant communities that still speak "the old way". I know some Brazilians of Japanese descent who've moved "back to" Japan. They take Japanese language lessons and the instructors always know to tell these folks "don't talk like your parents/grandparents", since the lingo on the mainland has shifted significantly.

I've also heard the rumor that this is why the US and UK speak differently, and that the US is actually how Britain used to sound, but I've also seen people say it's BS.