Prince Harry is acutely aware of the rumors about his "real father."
For decades, there's been speculation that Princess Diana's former lover James Hewitt is the 38-year-old's true father (despite the fact that Harry was born in 1984 and the couple's romance reportedly started in 1987.)
"Pa liked telling stories, and this was one of the best in his repertoire," Harry wrote in the book, per NBC News. He said Charles used to joke, "'Who knows if I'm really the Prince of Wales? Who knows if I'm even your real father? Maybe your real father is in Broadmoor, darling boy!'"
Recalling how Charles would "laugh and laugh," Harry went on to say it was "a remarkably unfunny joke, given the rumor circulating just then that my actual father was one of Mummy's former lovers: Major James Hewitt."
"One cause of this rumor was Major Hewitt's flaming ginger hair, but another cause was sadism," Harry shared. "Tabloid readers were delighted by the idea that the younger child of Prince Charles wasn't the child of Prince Charles. They couldn't get enough of this 'joke,' for some reason. Maybe it made them feel better about their lives that a young prince's life was laughable."
However, Harry set the record straight by noting in his memoir, "Never mind that my mother didn't meet Major Hewitt until long after I was born, the story was simply too good to drop."
James Hewitt, now 64, has also denied the claims, suggesting in 2017 that the rumor only continues to circulate because it "sells papers." He added, "It's worse for him probably, poor chap."
Buckingham Palace declined to comment on the book's allegations when contacted by NBC News. (E! is a member of the NBCUniversal family.)
Read on for more bombshells from Prince Harry's book, out Jan. 10.
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Spare by Prince Harry
For more revelations from Prince Harry, check out his book Spare.