President Donald Trump and King Charles III are distant cousins linked through a 16th-century Scottish nobleman, according to detailed genealogical research, by Robert Hardman, the official biographer of late Queen Elizabeth II and King Charles.
The discovery added an unexpected layer to the modern U.S.-U.K. alliance.
Hardman reported that both men share a common ancestor in the 3rd Earl of Lennox, a great-grandson of King James II of Scotland, making Trump and Charles III 15th cousins, The Daily Mail reported.
The earl met a violent end in 1526 after being captured during a power struggle over the young King James V and murdered by a rival known as the Bastard of Arran, Hardman reported.
The lineage flows through the earl's descendants to Lord Darnley, husband of Mary, Queen of Scots, whose son became King James I of England — a pivotal figure in the royal line that ultimately leads to the House of Windsor.
On the American side, the connection runs through Lady Helen, daughter of the Lennox line, who married into the Sutherland family. Generations later, her descendant Lady Jane married a chief of Clan Mackay.
Their son, the much-married Donald Mackay, became the 1st Lord Reay and a staunch royalist who fought for King Charles I during the English Civil War.
Donald Mackay's loyalty came at a cost. He was imprisoned, later exiled to Denmark — where he died — and at one point was even briefly held in the Tower of London by the king to prevent him from engaging in a duel — a detail Hardman highlights as an example of the turbulent personalities in the shared family tree.
From Mackay, the lineage continues through the Mackay and MacLeod families — including multiple figures named Donald — before reaching Mary Anne MacLeod of the Isle of Lewis.
She emigrated to the United States in 1930, married property developer Fred Trump, and became the mother of five children, including President Trump, born in 1946.
The research, compiled by veteran genealogist Robert Barrett, a former Daily Mail research editor, relied on land records, church documents, and Scottish peerage archives to overcome long-standing gaps in historical recordkeeping.
One complication involved Trump's ancestor Donald Mackay, whose daughter's multiple marriages, first to a Macdonald and later to a clergyman, Hugh Munro, obscured the lineage before it was clarified.
The findings also link Trump to the royal houses of Norway, Sweden, and Denmark through shared descent from King Christian I of Denmark, a connection that casts a fresh light on Trump's past interest in Danish-controlled Greenland, now under King Frederik X.
While the genealogical discovery adds intrigue, British officials are simultaneously dialing back use of the phrase "special relationship" to describe ties between Washington and London.
A senior government source told The Daily Mail that diplomats now prefer alternatives such as "enduring relationship" or "extraordinary alliance," viewing the older term as somewhat boastful and potentially irksome to other allies.
The shift predates the current administration and is unrelated to any recent tensions between Trump and British Prime Minister Keir Starmer, the source said.
Even so, recent engagements suggest the relationship remains robust. President Trump and first lady Melania Trump informally welcomed the king and Queen Camilla to the White House with tea and a tour of the presidential beehives, ahead of a formal ceremonial event.
The royal visit followed a Washington garden party hosted by Charles and the queen at the British Embassy, where about 600 British and American guests gathered for scones, clotted cream, and tea, for one of the most sought-after invitations in the capital this year.
Hardman also recounted Trump's long-standing admiration for the monarchy.
"I had a really good relationship with her. She was unbelievable. I liked her, and she liked me," Trump said of the late Queen Elizabeth II, recalling their 2018 meeting that ran far longer than scheduled and led to a full state visit in 2019, the last of her reign.
Trump has expressed similar regard for Charles.
"He's fantastic, and he has fought very hard. He's a fighter," Trump said. "We're close.
"I have a really good relationship with him. He's a great guy, and he's grown so much in the last 10 years and especially over the last couple of years as king," he added.
The newly uncovered ancestry comes with a historical irony. Through the same royal line, Trump is also related to King George III — the British monarch whose rule over the American colonies ended with independence in 1776, an event the U.S. is marking with its 250th anniversary this year.
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