Prince William and Kate Middleton's children -- Prince George, Princess Charlotte, and Prince Louis -- are raring to celebrate and can't wait for Christmas. The Cambridge kids have apparently written their letters to Santa Claus and have been asking their parents to set up the Christmas tree.

According to an insider, the children's favorite time of the year is the Christmas holidays and they have been quite eager to decorate at home. It comes as Kate's mother, Carole Middleton, said that her grandchildren usually help out with the Christmas decorations at the Middleton mansion. However, this year, George, Charlotte, and Louis will help her through a video Zoom conference call because of the COVID-19 restrictions.

The source also revealed that Prince George is growing up to be a well-behaved child and is acting a lot like a future king. He likes airplanes and helicopters, and he can't wait to grow up so he could start diving. The seven-year-old Cambridge royal is apparently obsessed with marine biology.

On the other hand, Charlotte and Louis have similar personalities and are cheekier than their older brother. The two children get along doing yoga routines, but Charlotte takes the lead in teaching Louis the poses.

The Cambridge siblings made an anniversary card for their great-grandparents, Queen Elizabeth and Prince Philip, who celebrated their 73rd wedding year on Nov. 20. The Duke and Duchess of Cambridge took to Instagram to share a close-up of the colorful photo, where the number 73 pops up from the paper.

George, Charlotte and Louis spent a brief summer at Queen Elizabeth's summer home in Balmoral in late August. It's unclear if the royal family will get together in Sandringham for Christmas since the pandemic lockdown orders are still in effect.

Meanwhile, Queen Elizabeth is apparently aware that Charlotte is a lot bolder than George. At one royal engagement a few years back, a child asked the royal grandmother if George looks after his sister. Her Majesty apparently replied that it is the other way around -- it's Charlotte who keeps on the lookout for her older brother.

Sources said that Charlotte is growing more confident through the years while George is developing into his future role. It's not clear, however, if he's already aware of his destiny. His father, Prince William, was told about being the heir to the British throne around the same age as George.