The era of Maury-Povich politics is officially upon us, after President Donald Trump suggested at a rally in Montana last week that Senator Elizabeth Warren be subjected to a DNA test.

“I shouldn’t tell you ’cause I like not to give away secrets… Let’s say I’m debating Pocahontas,” the president said, reviving his favorite racist nickname for the senator. “You know those little kits they sell on television for $2…I’m gonna get one of those little kits and in the middle of the debate, when she proclaims that she’s of Indian heritage, because her mother says she has high cheekbones…we will take that little kit…but we have to do it gently, because we are in the Me Too generation… I will give you $1 million to your favorite charity, paid for by Trump, if you take the test and it shows you’re an Indian…I have a feeling she will say no.”

Trump isn’t the first to recommend that Warren take such a test. “All the senator needs to do is spit into a tube, wait a few weeks and get her answer,” the Berkshire Eagle ’s editorial board wrote in March. But now the president is daring a potential 2020 challenger take a DNA test. Once again, Trump is setting a dangerous precedent.

Shortly after the 2008 presidential election, the New England Journal of Medicine published a perspective titled “The Genetic Privacy of Presidential Candidates,” which warned politicians running for office about a threat it called “genetic McCarthyism.” Because genetic information is so easily misinterpreted and misrepresented, the authors argued, presidential campaigns should resist calls to release candidates’ genomic information and pledge not to attempt to obtain or release the genomic information of their opponents.

“You want to undercut somebody’s political ambitions? Find a mutation,” says Sheldon Krimsky, a professor at Tufts University who studies the bioethics of genetic engineering. “What if one of them has the mutation for late onset Alzheimer’s disease? It’ll become a big story.”

Perhaps even more intriguing than Trump’s challenge to Warren, was the notion that he was giving away “a secret,” and his confidence that the results wouldn’t reveal Native American ancestry. Is it possible Trump already knows the results of an Elizabeth Warren DNA test? People have been surreptitiously collecting DNA for years. Police do it regularly — investigators collected garbage to confirm the Golden State Killer’s identity and again recently to match DNA collected at the crime scene of a brutal 1987 killing with a suspect. Ancestry hobbyists have stalked relatives who were unwilling to participate in their research. In April, 2009, a “national human intelligence collection directive” issued by the State Department directed U.S. diplomats to collect DNA of officials from Rwanda, Congo, and Burundi.

As home-testing kits become more affordable, anyone who sits across from a candidate at an Iowa pancake breakfast may soon, conceivably, have access to that candidate’s DNA. Every glass, fork, or handshake could be harvested for traces of the candidate’s most intimate information.

The desire for genetic privacy has actually spurred some security measures. Madonna reportedly deploys her own DNA sterilization team to clean up her dressing rooms after concerts and just last year she sued an auction house to block the sale of her personal letters, saying in a court filing that “my DNA could be extracted from a piece of my hair. It is outrageous and grossly offensive that my DNA could be auctioned for sale to the general public.”

She’s not alone. Navy stewards reportedly cleaned up president Obama’s bed sheets, perhaps influenced by a Scranton-area man who’d put Obama’s half-eaten breakfast up for sale on Ebay. “His DNA is on the silverware,” the advertisement read.

Warren has already been targeted by someone who tried to collect her DNA surreptitiously at least once before. In 2012, a Boston shock-jock sent one of his “guys” to a Warren book signing with the intent of collecting her DNA. After the senator pulled the cap off a pen with her teeth, the “guy” collected the cap and the shock-jock sent it to a DNA testing lab. There wasn’t enough saliva to run the test, according to the shock-jock. While some states have laws against the surreptitious collection of DNA material (including Massachusetts), federal law is opaque at best.

If Warren has ever taken a DNA test, so far she’s refused to release the results. When asked about the Berkshire Eagle’ s editorial on Meet the Press , Warren told Chuck Todd the story of her ancestry as it had been relayed to her as a child, a response she has now offered many times. “I know who I am,” she said.