Apparently Prince George got this "dreadful" Christmas habit from Prince William
And it's hilarious.
The Mountbatten-Windsors are the most talked-about in the world, with the Wales family in particular being front and centre this Christmas.
Royal Christmases are like no other, with the Mountbatten-Windsors giving each other joke presents at 6pm sharp, entering the room in order of title and getting weighed before and after lunch - a royal tradition to see if they have been fed enough.
But while the planned events may seem completely different to our festive schedules, there are some activities that even a royal title doesn't exempt you from, with Prince William revealing a "dreadful" Christmas habit of his eldest son, Prince George, a few years ago.
According to the now Prince of Wales, Prince George had been found in previous years "already opening his presents" in the week before Christmas, something that apparently his father and late grandmother Princess Diana did before him.
Yes, this naughty Christmas habit is over three generations old.
The revelation came from letters Princess Diana wrote to a friend in 1985, where she reportedly explained that William was following after her in terms of the mischievous habit of opening Christmas presents early.
"I could not resist opening my presents, as a parcel of any shape or form has never been safe with me," the late Princess of Wales explained in the letter. "I fear that William has also picked up this dreadful habit from his mother, as I find wrapping paper undone in the most extraordinary places!"
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It is not known whether Princess Charlotte and Prince Louis have followed suit, but given their mischievous streaks, it wouldn't surprise us.
The three Wales children, Prince George, Princess Charlotte and Prince Louis, have been front and centre this Christmas, even photographed helping at a baby bank with their mother, the Princess of Wales. Not to mention, the three miniature royals joined their parents for the famous Christmas Day walk to church in Sandringham.
It is not known however how the family celebrated Christmas behind closed doors.
We will continue to update this story.
Jenny Proudfoot is an award-winning journalist, specialising in lifestyle, culture, entertainment, international development and politics. She has worked at Marie Claire UK for seven years, rising from intern to Features Editor and is now the most published Marie Claire writer of all time. She was made a 30 under 30 award-winner last year and named a rising star in journalism by the Professional Publishers Association.