Prince George and Princess Charlotte's personalities mimic Prince William and Prince Harry's

Prince George, 6, Princess Charlotte, 4, and Prince Louis,1, tend to steal the spotlight at every royal outing they attend, much like Prince William and and Prince Harry did during their childhood years. But that's not the only thing the children seem to have in common with their elders.

An insider recently revealed to PEOPLE that George and Charlotte's personalities already mimic that of their father and uncle's.

“George is more reserved, and Charlotte is more outgoing,” the insider said. “Maybe it’s because he’s the heir and one day he might be King.”

“It’s the same difference between William and Harry,” they added. “Harry is much more laid-back and William is the more serious one because he will be King one day.”

The royal children's personalities were on full display at the inaugural King's Cup put on by the Duke and Duchess of Cambridge earlier this month. While George watched the race closely with his new toothy (er, toothless) smile, Charlotte famously made headlines for sticking her tongue out at her grandfather (a move originally made famous by Harry).

PEOPLE noted that although George will one day hold the highest royal title, Prince William and Kate Middleton treat all of their children the same. The Sun reported earlier this year that the royal couple even made the decision to wait to tell George about his royal status until he's much older.

"I love my children in the same way any father does, and I hope George loves me the same any son does to his father. We are very normal in that sense," William said.

In another attempt to be "very normal," the Cambridge siblings will go to the same private school.

While it might not seem like a big deal, many royal children before them were taught by a governess at home or sent to boarding school. Prince William became the first future king to attend public school alongside Prince Harry, thanks to the insistence of their mother, Princess Diana.

"The decision to have William, 3, develop his finger-painting skills among commoners showed the influence of Diana, Princess of Wales, who had worked in a nursery school herself when she was just a Lady," a Newsweek article stated back in 1985.

Charlotte will join George at Thomas's Battersea London Day School on Sept. 5.

“She can’t wait to be with George at big school,” the insider said. "They are close in age, and they spend so much time together... Playdates [with outsiders] can be tricky, so they learn to lean on each other.”