Dear David,
You must surely know the phrase, "an accident of birth". Through an "accident of birth" my brother has dual Maltese and British nationality (born in Malta to British parents, father serving in Royal Navy). YOU personally had nothing to do with where YOU were born. By all means be proud of what your forebears did, but pride in where you were born? That's pretty weird and irrational.
And I know it is. As I said in another post, I'm glad to be a Cornishman, and feel sorry for others who do not have that good fortune. As soon as I examine my own feelings, though, I can see that for the joke that it is. We are all capable of irrationality. It's just that some of us are also capable of recognizing it when we think about it.
Finally, the whole idea of "leaving for a better life in America" can quite easily be turned on its head. Perhaps there are those who are proud that their ancestors didn't run away to a foreign country, but stayed and built the nations in which they were born. Put like that, it sounds like an insult. But then, "America is the greatest" can sound like an insult too, if it carries the implication that all other nations are inferior.
Cheers,
R.