Kate Middleton jokes only one child looks like her - but who?

Prince George, Princess Charlotte or Prince Louis?

Kate Middleton is often the mastermind behind the sweet family portraits, which are released to mark her children's birthdays.

When the images are released many fans draw comparisons between the siblings, as well as the children and their parents the Duke and Duchess of Cambridge.

In Prince George's recent ninth birthday portrait some claimed the oldest of the Cambridge family looks very similar to his dad Prince William.

Princess Charlotte has also been told she looks very similar to her father, while the youngest of the brood, Prince Louis, is said to resemble his mother.

We are not the only ones who think Louis is Duchess Catherine's double, as the 40-year-old royal thinks the same.

A friend close to Kate told PEOPLE: "Everyone always comments on how Louis is the spitting image of Kate.

"She loves it and thinks it's very sweet — she often jokes that he's the only one of her kids who actually looks like her!"

Not only is Louis Kate's double, based on their appearance, but they also have the same interests too.

Kate has made it known she loves tennis, as she is often spotted court-side at Wimbledon, and her little ones are following in her footsteps. 

In a conversation with tennis ace and Wimbledon champion Novak Djokovic Kate revealed all her children are practicing their forehand and backhand.

When the duchess handed Novak his honour at this year's Wimbledon, Kate said: "George is playing. They're all playing, even Louis who's four. They're all keen."

Kate has previously been spotted at exclusive sports club, The Hurlingham Club, playing tennis with her children and last year she even showed off her skills on the court to US open winner, Emma Raducanu when the pair played doubles.

At the event at the National Tennis Centre in south west London, the tennis star praised Kate’s skills, saying she was “very, very impressed” and that “her forehand is incredible.”