They might be Britain's most famous family, but the Duke and Duchess of Cambridge have made it clear that they want their children to be as grounded as possible.

According to US Weekly, Prince William and Kate Middleton are striving to make things "normal" as Prince George, four, and Princess Charlotte, two, grow up in very abnormal circumstances.

Like any other children their age, George is said to "love anything on wheels" while Charlotte is a fan of Disney princesses, ironically. A friend told the publication: "I don't think it's quite dawned on her that she's a princess herself."

What we also know is that George is a budding tennis player and doesn't like doing European royal tours, which may be a problem if his future duties are anything to go by.

The tots are not spoiled by Kate and William, with iPads being banned from the home.

A source said: "They're very much seen as Mummy and Daddy's toys, not for children. . . As two people who grew up without gadgets for entertainment themselves, William and Kate are firm believers in toys, outdoor play, and encouraging an active imagination. They're very much a normal family."

IBTPOTY2017 Pictures of the week
19 July 2017: Prince William, Kate Middleton and their children Prince George and Princess Charlotte arrive at Tegel airport in Berlin, Germany Steffi Loos/AFP

It is undoubtedly challenging for the Cambridges to lead a normal life, with hundreds of photographers greeting them on every trip they make and the world awaiting new pictures of the children every birthday.

And apparently George – who had a few sulks on the family's royal tour of Poland and Germany recently – is catching on. The young prince has realised that his existence may not quite be the same as his four-year-old peers.

Prince George
The Duke and Duchess of Cambridge have released an official portrait of Prince George to mark his 4th birthday AFP/Getty

The source added that George is "at an age where he's starting to realize that the world he lives in is different to his friends." He is also starting to question dad William when they go biking together, as the insider added: "He's full of questions and curiosity about everything around him . . . He's growing up to be a very confident young boy."

Something that may come as a surprise is that Charlotte is apparently a mummy's girl. "Wherever Kate goes, so does Charlotte," the source states.

The two-year-old may also have a culinary future ahead of her since she sets up "her own toy set by her side to imitate" Kate or the housekeeper preparing food in the kitchen.

There seemed to be a bit of rivalry between George and Charlotte when the family touched down in Berlin. Charlotte was given her own mini spray of flowers by German gov rep Till Knorn and also shook hands with British defence attache Brigadier Rob Rider, to onlookers' surprise.

A perhaps overshadowed George soon began crying and tugging on his mother's coat for attention, and William was seen giving him some words of encouragement to behave better.

The royals visited Brandenburg Gate and the Holocaust Memorial during their trip, with the duke and duchess meeting Holocaust survivor Leon Henry Schwarzbaum, who shared his story with them.

One thing is not in doubt: we will be seeing a lot more of the prince and the princess in the not-too-distant future.

Prince George celebrates 4th birthday with official portrait Wochit