“Failure to Launch” is the name of a new book with the intriguing subtitle “Why Your Twentysomething Hasn’t Grown Up…and What to Do About It.”

Parents live in hope that their adult children will be actual adults, making their own way and moving out of the house in a timely manner. But what if that child is thirtysomething and royal?

Prince Harry and Meghan Markle aren't exactly your typical adult children clinging to their parents' apron strings, but they've announced that they're stepping back from frontline royal duties and looking for a more independent route. That silver spoon in Harry's mouth will probably be tough to fully dislodge, though.

Do you really have to worry about your next paycheck when you can toss out social media statements like this?: “We now plan to balance our time between the United Kingdom and North America, continuing to honour our duty to The Queen, the Commonwealth, and our patronages.”

RELATED: Pondering your grown kid's 'failure to launch'? Look in the mirror

But maybe your unmovable progeny is a 32-year-old Emmy-nominated actor?

Michael B. Jordan, though, seems a little more typical. He loves his mom's cooking, and that's why, though he's finally moved out of his parents house, it's just a short distance away. "You know … Sunday dinner. Mom and dad, they cook," he said on "The Ellen Degeneres Show" on Wednesday. A big batch of his mom's delicious mac and cheese is a powerful magnet.

This situation is nothing new, of course. Back in 2006, an unrelated movie called “Failure to Launch” explored the same issue with Matthew McConaughey as the beloved son turned tenacious tenant. But, it might be more prevalent these days.

According to the U.S. Census Bureau, 1 in 5 men ages 25-34 lived in their parents’ home in 2019. That compares to 13.1% of women that age living at home.

In all, there are 4.6 million men and 2.9 million women ages 25-34 living with their parents, for a total of 7.5 million still living at home, more than double the number living at home in 1980.

Most of those with a case of arrested development are in an entirely different world. It’s almost like the real one that most of us live in, where we have to earn our own living, but not quite. They just never grew up, according to “Failure to Launch” author and clinical psychologist Mark McConville.

"They perpetuate so many of the patterns we associate with adolescents — relying on adult oversight and management even while complaining about it," he told the AJC's Gracie Bonds Staples in a recent interview, "neglecting the sorts of mundane administrative responsibilities required to keep an adult life on track, failing to take ownership and initiative in preparing for their future."

You can try an eviction notice, as 30-year-old Michael Rotondo’s parents did. But there are more proactive and less extreme things parent can do to dislodge the recalcitrant offspring, according to McConville.

"Everyone wants to support their children; nobody wants to enable them," McConville said, and his book offers tips for striking the right balance, even providing goals for both children and their parents. 

There’s no guarantee on getting that well-adjusted adult, but maybe one day you can celebrate like Michael B. Jordan’s parents.

“I’m pretty sure they saged the entire house when I left,” Jordan said on “The Ellen Degeneres Show” on Wednesday. “Like, they lit incense and bleached it down and got rid of all of me and then I got a place.”

You can bet he’ll be back for that mac and cheese, though.