And, you're probably not.
One of the biggest myths held by white Americans today is that they all have a Navajo princess or Choctaw warrior-king buried somewhere in the genetic family attic. I can't tell you how many perfectly white-looking people have told me this in my years, including a good friend from college who looks about as "Indian" as Donald Trump. But geneologists who've noted this oft-claimed heritage and looked into it have debunked it.
How does it come to pass? I think part of it sounds romantic: we whites hold American Indians/Native Americans in high regard as a proud, mysterious people (this is unlike blacks... you will never hear whites brag that they have a black ancestor), and gives them a little "multiculti cred" to boot. In America, you're worthless if you're just "white," but if you can claim some exotic ethnic ingredient, well, we all look up to you as "cool." Everthing enforces this message... the media, movies, schools, magazines, you name it. White is boring, anything else is "interesting." Whites are then prompted to hate themselves and want to deny their own whiteness... so, they listen to jazz, wear Bob Marley shirts in college, go volunteer in the inner city, learn Spanish, decorate their houses with African masks, whatever. My parents-in-law have all these paintings and sculptures of black Americans all over their house, for instance (portrait of MLK, etc.).
Ward Churchill is a great example:
Tim Giago: Claiming Indian Heritage Becomes Popular
This guy has ZERO Indian heritage, but claimed it for the career-boosting effect, even dressing up in Indian clothes and beating war drums and stuff.
I think we can probably expect more of these bogus white claims to being multicultural as time goes on. But they're just fucking pathetic, I say. Whites -- and Western Civilization -- have nothing to apologize for. The non-whites of this planet have twice the lifespans they would otherwise thanks our contributions to technology.