She has provided no documentation that proves she is Native American instead she said that her family told her that she was, so she assumed it was true and ran with it. Keep in mind, many people have told her that all she has to do is to turn in her DNA to a place like ancestory.com and that would be good enough, but she hasn't done it. Why won't she do something so easy to get rid of the controversy? There's only one realistic answer.
By the way, the Boston Globe had to retract an article they provided that stated they had proof that Warren wasn't lying. They got caught providing fake news. The above isn't the only tremendous insight into her character there are plenty of negative stories about Warren, but this doesn't matter to Democrats who consider her to be a superstar.
Of course they also tried to force Hillary on the country but it didn't work because more people than naught said character matters and they didn't trust Hillary more than they didn't trust Trump.