Princess Mary has had a front-row seat watching her husband Prince Frederik battle to shake off his playboy reputation, earned from years of womanising and partying before he finally settled down with his bride.
Now, the Aussie princess has confided to friends that her greatest fear is her eldest son, Prince Christian, who has just turned 15, will go "down the same rabbit hole" as his father.
According to Danish press, Christian, who is second in line to the throne behind his 52-year-old father, is already planning a gap year for when he finishes the final three years of higher education.
"The alarm bells are already ringing for Mary," a source tells Woman's Day.
"She worries Christian will let loose after he finishes school, and she doesn't begrudge him that, within reason. But his dad copped a lot of flak in his bachelor years for his penchant for clubbing and bedding models – only for Christian, it will be worse since it's the age of mobile phones and social media."In Scandinavia, royal kids are usually left alone by the press but once they're 18, all bets are off."
An insider close to Amalienborg Palace says Christian is growing up to be a "wonderful, kind young man – but he has a rebellious streak".
"He's got a devilish sense of humour that so reminds Mary of a younger Fred, which isn't totally a bad thing, of course," says a source.
"He enjoys playing pranks on his parents and siblings, and is reaching the stage where he's interested in hanging out with friends and pretending he's a civilian.
"Mary is keen to impress on him he has more responsibility than his friends, given the world's eyes are on him, but she doesn't want to push him so far that he begins pulling away.
"It's a tricky time in any young man's life, let alone if he's one day going to be king."
When it comes to his gap year, a plan also followed by fellow royal rebel Prince Harry when he graduated high school, it's believed Mary, 48, is encouraging her eldest son to head to her homeland.
"She'd love to see him go to Australia and connect with his roots, perhaps by working on a cattle station or something environment-based," says a source.
"New Zealand is another option. Christian has made noises about going to the US, but Mary fears that could be one big party, so she's trying to gently steer him away from that."
We're told Mary is also pushing Fred to scale back his royal duties and spend more time with his son.
"She's keen for him to use the next three years to prepare Christian for becoming king," says a source. "It makes sense, and Christian can learn first-hand what not to do!"
Princess Mary has spoken of her pain at being separated from her Aussie sisters and brother due to Australia's strong pandemic border closure, according to Danish magazine Se & Hor.
"It has been three years since the Crown Princess last visited her family in Australia," says the magazine.
"Now she can't travel because of COVID-19 restrictions and they must stick to telephone conversations."
Mary's siblings Patricia, Jane and John, along with a bunch of nieces and nephews, are scattered around Australia, while her father John and his wife Susan have moved from Tasmania to his native Scotland.
"Mary hasn't been seen with her father for a long time," reports the local publication. "At Christmas in 2018 he attended a concert with the family."