Washington (CNN) President Donald Trump trades on identity politics, and that is what he's doing with Sen. Elizabeth Warren. Though the angle is different, it's reminiscent of his earlier remarks about Barack Obama's birth certificate. In both cases, Trump is using their identities against them.

You can tell at this point that Warren has had practice answering questions about her claims of Native American heritage because the Massachusetts Democrat been replying the same way for years.

Six years ago, when Warren first faced questions about her heritage and the accusation -- which she has repeatedly denied -- that she may have traded on having Native American ancestry for career advancement, she answered pretty much exactly the same way she answers now.

Here's what Warren said in a TV ad released by her Senate campaign in 2012, when her opponent, then-Sen. Scott Brown, a Massachusetts Republican, was raising the issue and demanding she release proof, somehow, of her Native American roots. It was among his main lines of attack against her

"As a kid, I never asked my mom for documentation when she talked about our Native American heritage. What kid would? But I knew my father's family didn't like that she was part Cherokee and part Delaware, so they had to elope.

The Boston Globe did exhaustive work back then drilling down into Warren's career as a law professor and whether she indeed got any benefit from portraying herself as Native American

Here we are six years later, Warren is running for re-election to her Senate seat and is an oft-discussed possible presidential contender in 2020, and her heritage is still the subject of questions. On Sunday, she was asked on NBC about a demand by a Massachusetts newspaper that she submit to a DNA test that would, presumably, be able to determine if she has any Native American blood.

She answered with more of her childhood.

"My daddy first saw my mother when they were both teenagers. He fell in love with this tall, quiet girl who played the piano. Head over heels. But his family was bitterly opposed to their relationship because she was part Native American. They eventually eloped. ... And that's the story that my brothers and I all learned from our mom and our dad, from our grandparents, from all of our aunts and uncles. It's a part of me, and nobody's going to take that part of me away."

She told the same story, essentially, to CNN's Jim Acosta on Sunday, when he asked about Trump's "Pocahontas" nickname for her.

JUST WATCHED Warren responds to Trump's 'Pocahontas' slur Replay More Videos ... MUST WATCH Warren responds to Trump's 'Pocahontas' slur 02:11

On CNN, she went a step further and said she had told Native American leaders she would use the ribbing from Trump against him: "Every time President Trump wants to throw out some kind of racial slur, he wants to try to attack me, I'm going to use it as a chance to lift up their stories."

She then said that more than half of Native American women in this country have been the victims of sexual violence, often by non-Natives. She said the federal government should do more about that.

In both interviews Sunday, she said, "I'm not running for president," but she also would not pledge on NBC to serve another full six-year term. Read more from CNN's Chris Cillizza on that particular word choice from her

If she does run for President, you can bet you're going to hear that story about her heritage a lot more.

The anatomy of her answer is to ignore the question asking for some sort of proof that she's Native American and rather to explain that this was the story she was told and so that's what she grew up believing. Anything beyond that, she's suggesting, isn't really important if she didn't get any benefit during her career from portraying herself as Native American. There's no direct evidence she did get a benefit, by the way, although Harvard Law School's PR department would mention her when they were asked about diversity.

It took some time back in 2012 for her to find the appropriate way to answer. She raised eyebrows at one point back then when she talked about her grandfather's high cheekbones. But ever since settling on what amounts to the that's the story I was told defense, Warren has stuck to it.

Sunday's question from NBC isn't the first time someone has suggested Warren take a DNA test; Brown said the same in 2016

Here's Warren speaking to Anderson Cooper in November of 2017, frustrated at Trump calling her Pocahontas during a code talker event at the White House.

JUST WATCHED Warren on Trump comment: I couldn't believe it Replay More Videos ... MUST WATCH Warren on Trump comment: I couldn't believe it 00:43

"He thinks he's going to shut me down with that," she said.

Stoking questions about a rival's heritage is nothing new for Trump.

But while the birtherism against Obama was treated with frustration and disdain by Obama's staff, Warren seems to be trying something different and instead using the issue against the President.

The point is that these side controversies have a way of coming back again and again. That will be doubly true if Trump continues to call Warren "Pocahontas." (Is there any question he won't?)

That Warren isn't even trying to dismiss it anymore suggests she realizes she needs to be ready for the long haul.