We might be used to the loving sights of Will and Kate, and Harry and Meghan, but royal marriages haven't always been so harmonious.
Back when marriages were often (unhappily) arranged, princes, princesses, kings and queens were prone to stray from their vows every now and then. Between royal mistresses, scandalous affairs and nights of drunken revelry, several royals over the years have ended up with children born out of wedlock.
And whether they've acknowledged them publically or not, royal-watchers have often found a way to find out the hidden truth.
Jazmin Grace Grimaldi and Alexandre Coste
Before Prince Albert of Monaco married the fashionable Charlene Wittstock and they welcomed twins, he had two illegitimate children. The first, a daughter named Jazmin Grace Grimaldi, was born to an American woman in 1992. After having her original paternity case thrown out in California, Prince Albert confirmed via a statement that he was Jazmin's father in 2006.
He has since invited Jazmin, now 25, to live and study in Monaco, although she has no rights to the line of succession.
The paternity of Albert's other child, Alexandre Coste, was also confirmed via a statement. Nicole Coste, the mother of Alexandre, is a former flight attendant who alleged that she had been receiving allowance and accommodation after the birth of her child. Prince Albert confirmed that he was the father of Alexandre in 2005.
Most recently, Jazmin has shared a slew of public posts in support of her father as he recovers from coronavirus, proving their strong bond after a rocky start.
"Prayers have been answered and my father has announced he is healed and healthy from the devastating Corona Virus! He is now free to go quarantine with family. This was very wonderful news to hear," she penned at the start of April.
Captain Mark Phillips, the husband of the Queen's daughter, Anne, Princess Royal, fathered an illegitimate daughter in 1985.
The girl, Felicity, was born to New Zealand art teacher Heather Tonkin. Phillips was confirmed as Felicity's father in 1991 after a paternity suit. He and Princess Anne divorced a year later.
Felicity is a half-sister to Zara Phillips and Peter Phillips, but has little contact with them.
Rumoured to have two love children, Michael Temple Canfield and Raine McCorquodale
Prince George, the younger brother of Kings Edward VIII and George VI, and Queen Elizabeth's uncle, was a noted "party prince" his entire life.
Reportedly enjoying affairs with both men and women, Prince George was notorious for his high-profile love scandals.
The Duke of Kent is rumoured to be father to two illegitimate children. The first, Raine McCorquodale, was born to Barbara Cartland, an author, in 1929 while she was still married to Alexander McCorquodale. Raine McCorquodale is, of course, known for being the stepmother of Diana, Princess of Wales.
His second child, Michael Temple Canfield, was allegedly born to American socialite Kiki Preston. Preston, known for her drug addiction and referred to as "the girl with the silver syringe," is said to have given birth to Canfield in 1926 after a long and dangerous affair. Both Prince George's brother, Edward, the Duke of Windsor and Laura, Duchess of Marlborough, had said that they believed this.
Baby Michael was adopted by Cass Canfield, and went on to marry Caroline Lee Bouvier, younger sister of First Lady Jacqueline Kennedy.
It has been a long-standing "open secret" that 51-year-old Belgian sculptor Delphine Boël is the daughter of former King Albert II of Belgium. The king reportedly had an affair with Baroness Sybille de Selys Longchamps, which resulted in Delphine's birth.
According to Delphine, her parents kept in contact for years, but her mother waited until she was 18 to tell her the truth of her parentage. When Delphine attempted to get into contact with him, he allegedly told her, "Leave me alone with that story. You are not my daughter."
However in January this year, the former King finally came clean and according to his lawyers, admitted to being her father "to put an end, with honour and dignity, to this painful procedure."
"Legally, he will end the legal battle there and accept that Delphine Boel is his fourth child," his lawyers said in a statement.
Alicia von Bielefeld and Alexia Grinda-Lejeune
Prince Bernhard of the Netherlands, the father of the former Queen Beatrix, also had two illegitimate children during his marriage to Queen Juliana. The first, Alexia Grinda-Lejeune, was allegedly born to his mistress Hélène Grinda, who he kept in a fancy Parisian apartment.
The second, Alicia von Bielefeld, was born to an American mother. Prince Bernhard only admitted to being her father a few months before his death, insisting that she "must be left alone."
Prince Carlos, Duke of Parma, a member of the Dutch royal family and head of the House of Bourbon-Parma, fathered a son out of wedlock in 1997. During his relationship with Brigitte Klynstra (before his marriage to Princess Annemarie), Carlos Hugo Roderik Sybren Klynstra was born.
In 2015, when Carlos turned 18, he petitioned the court to adopt his father's surname and be named a prince. A court judgement in 2016 ruled that Klynstra is legally entitled to the name His Royal Highness Prince Carlos Hugo Roderik Sybren of Bourbon-Parma.
However, he is not a member of the royal family or eligible to inherit the throne.
Prince Carlos reportedly opposed his son's court battle the entire way.
Ingeborg Verdun and an unnamed son
In the book Dramas in the Belgian Royal House, King Leopold III, the father of Albert II, is alleged to have had an illegitimate daughter.
According to the book, Leopold had lost his wife in a car accident in 1935 and started a relationship with Liselotte Landbeck. The union resulted in a daughter, Ingeborg Verdun.
Although it has never been confirmed, the same book also alleges that King Leopold was father to another child, a son. "It happened during the difficult years -1954 - '55 - after the Belgian royals returned home from Switzerland after the War."
Jason Jenkins and Simon Dorante-Day
Prince Charles? Oh my! Over the years, several reports have alleged that the prince may have fathered children out of wedlock. The first, Jason Jenkins, is the son of Canadian former navy lieutenant Janet, who claims she had an affair with Charles while he was still married to Diana.
"Ours was a long-distance romance… clothes used to be just ripped off and left where they dropped! At the time, neither of us used birth control or other protection. It was before AIDS and we just didn't think about it," Janet told The Globe.
Jason, who was born nine months after that encounter, is now 34.
The other rumoured love child is Simon Dorante-Day, an Aussie man who believes he's the son of Prince Charles and Camilla, Duchess of Cornwall. According to Dorante-Day, he was conceived before Charles' marriage to Diana. Charles and Camilla had been spotted together in 1965, and Camilla did 'disappear' for around nine months afterwards.
"I know that my story sounds unbelievable, but everything I say is checkable – if you don't believe it, check it," he told New Idea.
"I'm simply a man looking for my biological parents, and every road has lead me back to Camilla and Charles. I'm not in this for money or for a title – I simply want to know who my parents are."
Charles and Camilla have never commented on the matter and as the years roll on, these outlandish claims simply don't seem to stack up.