Re: marrying a girl from different ethnic setup
Expect to learn a few words of her language. Don’t expect her to conspire with her family in a language that you undersatnd. 
Seriously, I see no problem, if you people are compatible and have no communication barriers. I’m assuming that there’s at least one language that both the persons in question can communicate in. Otherwise, you’ll have difficult time using gestures that can be misunderstood. If the person is from Italy, never use this gesture: :k:
A good heart-to-heart talk can reconcile all language differences.
Brownie culture also dictates that. We just don’t want to have any culture.