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Siblings Prince George and Princess Charlotte are getting an early education on becoming British royals.

Royal historian and author Marlene Eilers Koening told Hello! Tuesday the children must bow and curtsy to their great-grandmother, Queen Elizabeth II, at public engagements.

“Certainly by age five,” she explained. “The only person they will curtsy or bow to is the sovereign. A royal highness does not curtsy to another royal highness. Yes, there are articles that state this, but it is not true.”

George, who turned five on July 22, will be expected to begin publicly bowing to the queen shortly. The magazine noted it’s likely that the future king has done so in private when greeting Elizabeth, 92.

Charlotte, who turned three years old in May, has a few more years before she begins following her brother, who is third in line to the British throne. However, she was spotted last summer giving a mini curtsy to diplomats while on a royal tour with her parents.

Their youngest brother Louis is three months old.

“Curtsying and bowing is etiquette, nothing to do with precedence," said Koening. "You bow or curtsey the first time you see the sovereign and then again when you leave.

"At Christmas at church, we saw the Cambridges and Prince Harry and Meghan [Markle] curtsy and bow when the queen arrived and left. Other royals including Charles did not because they had come from Sandringham and had already seen the queen.”

Women’s World added the royal children, who all have “His Royal Highness” or “Her Royal Highness” before their names, do not have to genuflect in front of their parents. They also don’t have to bow for their older relatives either.

But the children aren’t the only ones learning proper royal etiquette.

Sir William Heseltine, one of the queen’s private secretaries, revealed that members of the royal family should wait until the monarch retires to bed, before they also hit the hay.

In an interview for the book, “The Royals in Australia,” Heseltine shared that “nobody felt it right to go to bed before the queen did.”

While this tradition is something Markle may need to adopt now that she’s officially the Duchess of Sussex, it was something Princess Diana struggled with.

“For Diana the long royal evenings were agony,” he explained. “There’d be an hour or so in the sitting room of everyone sitting around making conversation, and nobody felt it right to go to bed before the queen did.

"And Diana was driven to such extremes that she’d excuse herself and go to bed, which was thought to be rather bad form going to bed before the queen.”

News.com.au noted the bedtime tradition isn’t the only rule the former “Suits” star will need to learn.

Last month, Twitter used claimed the 36-year-old had breached royal protocol after an Irish politician suggested she was pleased with Ireland’s abortion referendum result.

According to the UK Parliament website: “Although not prohibited by law, it is considered unconstitutional for the Monarch to vote in an election.”

Reports also surfaced that should Markle become pregnant, she is unlikely to be allowed to have a baby shower.

Royal expert Victoria Arbiter said throwing an elaborate baby shower is unheard of for members of the British monarchy.

“While the royals are very wealthy… a lavish baby shower would be seen as highly inappropriate… there’s nothing they can’t go and but themselves,” she told UK’s Daily Mail.