Donald Trump’s most obvious superpower is his lack of shame, which permits him to do things that ordinary politicians would never dare or survive. But perhaps his real gift is his ability to cause his opponents to beclown themselves.

So today, baited by Trump’s gibes, Elizabeth Warren rushes headlong into self-parody with a lavish rollout of a DNA test that suggests that she may be (checks notes) 1/1,024th Native American. The DNA test, notable for its imprecision, suggests that Warren may have a Native American ancestor somewhere “in the range of 6-10 generations ago.” (Which reminds me that I have an ancestry report around here somewhere suggesting that in addition to my Russian Jewish ancestors, I am also descended from Scottish kings.)

Despite the media hype, the new data seems unlikely to resolve the questions about Warren’s ancestry, even as it opens vast new territory for ridicule. More substantively, she exposes the unutterable silliness of the politics of diversity, at least as it practiced in the Ivy League. Her timing is especially awkward, given it comes on the same day that a trial begins in federal court exploring Harvard’s use of race in admissions.

The Boston Globe reminds us why this matters:

During her academic career as a law professor, she had her ethnicity changed from white to Native American at the University of Pennsylvania Law School, where she taught from 1987 to 1995, and at Harvard University Law School, where she was a tenured faculty member starting in 1995.

There’s no evidence this had any practical impact on her academic career, but the gods of diversity were appeased.

The political fallout has been less benign. Having fully exploited the “birther” conspiracy theories about Barack Obama for political advantage, Trump is obviously partial to using questions about racial identity and ancestry as cudgels. So not surprisingly, has behaved with typical Trumpian crassness on the subject, mocking Warren as “Pocahontas,” and telling Fox News last week: "She can't prove anything... You know what? I have more Indian blood in me than she does. I have none, unfortunately. I have none."

Trump even offered to donate $1 million to a charity if Warren went through with the DNA test. (Perhaps not surprisingly, he has since denied making that offer.) The mockery and the challenge have clearly gotten into Warren’s head and since she is running for president, she felt compelled to engage with Trump, if only to show that unlike Hillary Clinton, she knows how to fight back.

So now we get the Elizabeth Warren DNA show, complete with a slickly produced video. And we are all about to get dumber for it.

The Globe notes the iffiness of the whole thing:

The inherent imprecision of the six-page DNA analysis could provide fodder for Warren’s critics. If her great-great-great-grandmother was Native American, that puts her at 1/32nd American Indian. But the report includes the possibility that she’s just 1/1,024th Native American if the ancestor is 10 generations back.

The analysis was done by Stanford Professor Carlos D. Bustamante, a former winner of the MacArthur genius grant for his work on DNA. But he notes the limitations on a study of this sort.

Detecting DNA for Native Americans is particularly tricky because there is an absence of Native American DNA available for comparison. This is in part because Native American leaders have asked tribal members not to participate in genetic databases…

To make up for the dearth of Native American DNA, Bustamante used samples from Mexico, Peru, and Colombia to stand in for Native American. That’s because scientists believe that the groups Americans refer to as Native American came to this land via the Bering Strait about 12,000 years ago and settled in what’s now America but also migrated further south. His report explained that the use of reference populations whose genetic material has been fully sequenced was designed “for maximal accuracy.”

Bustamante’s analysis suggest that somewhere, someplace there are traces of Native American ancestry. Warren, he concluded, “has 12 times more Native American blood than a white person from Great Britain and 10 times more than a white person from Utah, the report found.”

So, we are left with the question: So what? Why do we care? What possible relevance does this miniscule detail have for Elizabeth Warren’s ability to teach the law or to make public policy? In what way did the ancestry of her great-great-great-great-great grandparents contribute to the diversity of higher education?

And why have we returned to this invidious form of racial identity?

In the South it became known as the "one-drop rule,'' meaning that a single drop of "black blood" makes a person a black. It is also known as the "one black ancestor rule," some courts have called it the "traceable amount rule," and anthropologists call it the "hypo-descent rule," meaning that racially mixed persons are assigned the status of the subordinate group.

Will this sort of thing henceforth be known as the Warren Rule?