It's not much to ask for .She should do the DNA thing. If she doesn't have the native backgroud, just do a mea culpa and apologize. If she has some native ancestry, she can tell all her detractors to fuck off.
Unless she lied.
All she has to do is take the DNA test.
The people who voted for her deserve to know.
Affirmative action scholarships she got from Harvard is a federal crime if she lied in her application to the school.