When people ask me where I'm from, it always makes me stop for a moment or two before I can answer. The easy answer is that I'm from Brazil, but that does not describe me at all other than the fact that I speak Portuguese. So I always follow the "I wouldn't have guessed" remark with a bit more of information. I tell them that my father's family came from Greece and Turkey, and that my mother's family came from Russia and Romania. I feel that this history describes me better than my country of birth. It integrates for my fair skin and my Mediterranean features, and sets me apart from the classical Brazilian mixture of Portuguese, African and native Indians.
Most people are amazed at how diverse my family history is, and how far back my family can trace its roots. Our family tree has about 10 generations in it, along with many of the parallel branches from people who married in. Not only do we keep track of our relations, but we correspond and interact even though people are spread around the globe. To keep my wedding small (Brazilian standards, 200 guests), we settled on inviting the portion of the family tree that included my grandparents, their siblings and their descendents. My paternal grandmother was upset that her cousins (and their (grand)children) were not included. It was hard to please everyone, but I did not want to overwhelm the groom... and his family of 4.
When we got married I warned my husband that it was a one-way street; people marry into my family, not out - regardless of how the relationship turns out. And that includes the spouse's family too, in-laws are not "out-laws". Most of the ex-spouses (and their families) are still invited to all social gatherings, and it does not matter whether you interact well or not with someone. Everyone is invited, they are family. The seating arrangements for my wedding took a week to put together, to make sure that the people that were not talking to each other at the time were seated at opposite ends of the ballroom. Some disputes are temporary, others are longer lasting... but in the end it is all family.
Moving to the U.S., I was introduced to the concept of a nuclear family: parents & kids. It was a foreign concept for me, what about the cousins? If you ask my husband he will say that everyone is a "cousin" under my definition of family... but I don't think that is such a bad idea.