In class the other day we were discussing why it is that Americans always use their ancestry to describe themselves. In other words, why would someone claim to be Irish, French, German, etc., when their family has been in America for generations? That question is difficult to answer because it is one that is unique to our country and also because we are so accustomed to describing ourselves in this way that we do it without thinking.
Even so, I think that part of the reason that we feel the need to be associated with a nationality different than our own is because we like the idea of having something that sets us apart from the crowd. In America there is a huge stress on individuality, and being able to claim ties to a foreign country can make a person feel like they have something that is unique to them. Many Americans also, like most people around the world, take pride in their cultural heritage. The difference in this area between Americans and the rest of the world, however, is that we have been in our country for a relatively short period of time, so when we go back in our family trees many of us soon find connections to other countries. I think that knowing and identifying ourselves with the history of our family, which for most of us naturally includes a variety of different cultures, gives us a sense of legitimacy as well as a feeling of connection to the rest of the world.