The Prince and Princess of Wales reportedly have a “naughty” secret ingredient that keeps their high-profile marriage thriving. The royal power couple, who exchanged vows in the grandeur of Westminster Abbey back in April 2011, are proud parents to three adorable kids.

Kate Middleton and Prince William’s ‘naughty’ secret to a happy marriage: she’s “naughty” – he’s “dirty”…

With the world’s eyes fixated on them during public appearances, William and Kate’s dynamic seems refreshingly down-to-earth away from the spotlight. An expert claims a playful nature is the pair’s clandestine charm – a trait they’re also imparting to their children.

Author Christopher Andersen shared with Fox News Digital: “William once described Kate’s sense of humor as ‘naughty’ and his own as ‘dirty,’ and claimed that it was one of the most important things that drew them together. They’ve certainly cleaned up their act for the children’s sake, but they can still make each other double over laughing.”

Always caught sharing laughs during royal events, William and Kate radiate joy, while their young ones, particularly the spirited Louis, clearly inherit the family’s sense of fun.

Prince William first opened up about Kate’s playful sense of humor during their official engagement interview in late 2010. Speaking to Tom Bradby, William reminisced: “We obviously met at university – at St Andrews we were friends for over a year first and it just sort of blossomed from then on. We just spent more time with each other, had a good giggle, had lots of fun and realised we shared the same interests and had a really good time,” reports the Mirror.

He added, “She’s got a really naughty sense of humor, which kind of helps me because I’ve got a really dry sense of humour, so it was good fun, we had a really good laugh and things happened.”

Fast forward to today, the couple are now proud parents to three children, but it’s evident they still share that same spark. According to Anderson, the Waleses have a “wacky, slapstick, Monty Python-meets-Benny Hill sense of humor.”

This sense of fun is something they’ve passed on to their children, Prince George, Princess Charlotte, and Prince Louis.