Prince William reportedly asked his father, Prince Charles, a crushing question before the Prince of Wales divorced Princess Diana.
From their engagement in 1981, to their royal wedding the same year, Charles and Diana seemed like the fairytale royal couple at first.
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© PA/AAPThe Prince and Princess of Wales leave St. Paul's Cathedral in a carriage after their wedding.
They welcomed two sons, William and Prince Harry, in the early years of their marriage and all seemed well.
But behind the scenes the couple were grappling with a number of issues, from affairs to personal demons and royal spats.
In the lead up to their 1996 divorce, a young William supposedly realised just how bad his parents' relationship had become and asked his father a devastating question.
© Tim Graham Photo Library via GetPrince Charles, Prince of Wales and Diana, Princess of Wales at home in Kensington Palace with their sons.
"Why do you make Mummy cry all the time?" the young prince reportedly asked his father during an emotional dispute.
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The claim comes from royal biographer Robert Lacey's new book Battle Of Brothers: William and Harry, which touches on the boys' childhood.
According to him, William also told Charles "I hate you, Papa. I hate you so much," during the same argument.
As a child, William supposedly sided with his mother when it came to family disputes and felt "open disdain and aggression towards his father" over the state of their marriage.
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© GettyThe Prince and Princess of Wales attend a welcome ceremony in Toronto, 1991.
It likely didn't help that Charles' affair with Camilla Parker-Bowles was one of the worst kept royal secrets at the time.
He and Diana eventually separated and finalised their divorce in 1996, but sadly the 'People's Princess' died the following year in a tragic car crash.
Though they had split on poor terms, Charles was reportedly the one who travelled to Paris to collect his ex-wife's body and bring her home to the UK for a funeral.
Their two sons, just 12 and 15 at the time, walked behind Diana's coffin during her massive public funeral, their father at their side.
Lacey claims that the resentment William felt towards Charles for his treatment of Diana remains to this day, however if that's true, he hides it well.
The Duke of Cambridge has always seemed to have a close bond with Charles, at least in the public eye.
As Charles' heir, William will one day support his father as King, before taking on the role himself.