Its interesting how this topic evokes so much emotion from people. I believe it stems from only a generation ago, that when someone claimed to be something they weren't, they were called out on it, or declared mentally unstable. Somehow (correct me if I'm wrong) but I vaguely remember a film with randall tex cobb where he believed he was black, and everybody in the film knew he was nuts and treated him as such.
Now, we seem to play along and agree when someone claims to be something they are not. The emperor has no clothes is no longer called out. Elizabeth Warren has been rewarded for the claim of being a Native American, a position at Harvard, in the government, and now a Senate seat.