GQ just published something revealing about Melania Trump, and this time it doesn't involve partial nudity.

The men's magazine apparently turned up a half-brother of the would-be first lady in her native Slovenia. His name is Denis Cigiljnjak and, according to GQ, "Viktor Knavs, Melania's father, has never acknowledged Denis' existence, and Cigiljnjak is sure that until now, Melania and her sister did not know of him." GQ reported that Melania Trump initially denied any relation to Cigiljnjak but, when presented with court documents later, claimed she hadn't understood the mag's inquiry and said she had actually "known about this for years."

In other words, even as he collects Republican National Convention delegates, Donald Trump might have picked up a half-brother-in-law, too.

This is hardly the first time the media discovered a relative that a president or White House hopeful didn't know about -- or, in some cases, did but tried to keep hidden. In fact, it's a something of a political media pastime that goes back more than 200 years.

In 1802, journalist James T. Callender reported in a Richmond, Va., newspaper that President Thomas Jefferson "kept, as his concubine, one of his own slaves" and that he had fathered "several children" by her. The slave in question was, of course, Sally Hemings, whom Callender identified only by her first name.

Historians have long debated the accuracy of Callender's report -- Jefferson never made a public admission, and his descendants denied it for decades -- but the Thomas Jefferson Foundation concluded in 2000, "based on documentary, scientific, statistical, and oral history evidence …  that years after his wife's death, Thomas Jefferson was the father of the six children of Sally Hemings mentioned in Jefferson's records, including Beverly, Harriet, Madison and Eston Hemings."

Jefferson was the original John Edwards.

---

In 2012, NPR sent journalists to Mexico to interview Mitt Romney's second cousins, whom he had never met. The public broadcaster explained the connection:

"The Church of Jesus Christ of Latter-day Saints banned polygamy in 1890, but Mormon leaders quietly sent selected members to Canada and Mexico to continue practicing plural marriage. One of them was Miles Park Romney, the great grandfather of Willard Mitt Romney. Miles Park Romney -- a Utah builder with a massive head and a square jaw -- had four wives and 30 children.

"Today, some of their descendants still live about a four-hour drive from El Paso, in the Mormon colonies in northern Chihuahua, where mainstream Mormons no longer practice polygamy."

Reuters reached for an even more distant branch on the Romney family tree, finding fourth cousins in England who didn't know they were related to the 2012 GOP nominee.

"I saw him on the telly twice the other day -- last week, I think," said Jennie Iveson, a retired factory worker. "He looks a bit like my brother."

Tremendous insight.

---

In 2008, the Italian edition of Vanity Fair located a mysterious half-brother of Barack Obama living in Kenya. The then-senator from Illinois knew about George Hussein Onyango Obama, but had met him only twice and had not seen him in a couple years. George Obama's whereabouts were apparently unknown until Vanity Fair tracked him down in a 2-by-3-meter hut on the outskirts of Nairobi.

"I live like a recluse; no-one knows I exist," he told the magazine.

Also that year, multiple news outlets reported that Barack Obama's Republican opponent, John McCain, had two half-sisters-in-law -- contradicting his wife Cindy's description of herself as an only child. One of the sisters, Kathleen Hensley Portalski, came forward in August 2008, feeling ignored by the family during the campaign.

"It's terribly painful," she told The Washington Post.

Two months later, the Wall Street Journal told the story of Lillie McCain, who isn't related to the Arizona senator by blood but shares his surname because her great-great-grandparents were slaves on a Mississippi plantation owned by John McCain's great-great-grandparents.

---

Genealogical research can produce awkward results, but John Kerry embraced the work of the Boston Globe in 2003, when the newspaper revealed to him -- before publication -- that his grandfather, Frederick A. Kerry, had shot himself in the head at a prominent Boston hotel in 1921. The Globe also learned that Frederick Kerry had been born Frederick Kohn in Austria, but had dropped the Jewish name before immigrating to the United States. John Kerry, the 2004 Democratic nominee, previously knew none of these details, according to the Globe.

" 'How many times have I walked into that hotel . . .' said an emotional Kerry, his voice trailing off. He said it was the first time he had talked publicly about the suicide.

"Kerry said he learned about 15 years ago that his grandmother was Jewish. That led to years of unsuccessful efforts to learn more about his grandfather's roots and his own.

" 'This is amazing; that is fascinating to me,' Kerry said, in reference to the ancestral records. 'This is incredible stuff. I think it is more than interesting; it is a revelation. It has a big emotional impact, because it obviously raises [questions]: I want to know what happened, why did they do this, what were they thinking, what was the thought process, and why, once they got over here, why they never talked about it,' he said."

---

Bill Clinton made it through the 1992 campaign without any surprise relatives popping up in public, but just five months into his presidency, The Washington Post reported that Clinton had a half-brother, Henry Leon Ritzenthaler, who had tried unsuccessfully to contact him late in the race. Seven weeks after The Post identified Ritzenthaler, the Arizona Republic reported that Clinton also might have a half-sister, Sharon Pettijohn.

(Clinton's father, William Jefferson Blythe, married at 17 and divorced a year later. Months after the divorce, he and his ex-wife conceived Ritzenthaler, according to public records and the wife's account. Pettijohn allegedly was the product of a relationship between Blythe, a traveling salesman, and a different woman whom he married before the birth but soon divorced. All this happened before Blythe, who died at age 28, met Clinton's mother in 1942.)

In his 2004 memoir, "My Life," Clinton wrote that "when I read about Leon, I got in touch with him and later met him and his wife, Judy, during one of my stops in northern California. We had a happy visit, and since then we've corresponded in holiday seasons. He and I look alike, his birth certificate says his father was mine, and I wish I'd known about him a long time ago."

Clinton also wrote that he had received information confirming the report about Pettijohn and added, "I'm sorry to say that, for whatever reason, I've never met her."

Long-lost relatives can make fascinating stories, but the reality is they often fail to reveal much about presidents and candidates. How much can someone tell us about a person he or she has never met, or met only a couple of times?

Still, given the media's fascination with the subject, potential White House contenders should consider spending a little time on Ancestry.com if they don't want to be surprised.