Young Hollywood's rush to the altar

Miley Cyrus likes to spend her days playing with her dogs, skateboarding and watching television marathons of "SpongeBob SquarePants" -- activities she often chronicles on Twitter. Now, the 19-year-old has to fit a more adult activity into her schedule: wedding planning.

The singer-actress announced in June that she is engaged to 22-year-old "Hunger Games" star Liam Hemsworth -- and became the latest in a line of young Hollywood stars to head for the altar, even as Americans on average are marrying older than they used to, and many are skipping the nuptials altogether.

Hilary Duff -- who like Cyrus starred in her own show on the Disney Channel as a teenager -- married at 22 and had a baby in March at 24. Three years ago, the eldest member of the sibling boy band the Jonas Brothers, Kevin, wed at 22 and is starring later this month in an E! reality show about settling into married life. And though he has yet to pop the question, 18-year-old pop star Justin Bieber has been in a serious relationship with tween queen Selena Gomez, 19, for nearly two years.

Why the rush up the aisle for some young celebrities when the average marriage age for American women is 27 and for men 29? Industry observers and marriage experts say there are various forces at work: First, many of these stars come from religious or cultural backgrounds in which it's more acceptable to settle down early. They've also had professional responsibilities since they were

children, forcing them to interact with adults and possibly mature more rapidly. Plus, as fame and income increase, stars have a harder time finding people they trust -- so when they do, they hold on tight.

"Everything came so fast for me," Duff said by telephone, the sound of her infant son crying in the background. "I was financially secure and successful at my job and having to take on a lot more responsibility than the average 18-year-old. Plus, I feel like being in the dating world was never an option for me. I wasn't going to give just any! person my number. I didn't have an opportunity to meet people outside of the business."

Bonnie Liedtke, a manager whose former clients include Zac Efron and Leonardo DiCaprio, said the young stars she works with often are worried about socializing outside of small groups for fear of being exploited. "Being in this business tends to drive people to a smaller scope," said Liedtke. "People feel like they can only trust very few people now with social media and having photos taken in private situations. Dating somebody outside of that small circle can become very difficult."

Duff, who starred in the television series "Lizzie McGuire" from ages 16 to 19, met her husband, former professional hockey player Mike Comrie, through a trusted mutual friend. Once the pair began to develop strong chemistry, Duff said she experienced a level of ease with Comrie that she had never before experienced.

"When you're so well known, you're also extremely secluded. You don't have a normal life, and so when you find someone that you just love to be around and you're in love with and totally compatible with, there's so much a sense of comfort," she explained.

Although few stars go to such extreme lengths today, many are cagey with the press about their private lives. When pictures surfaced of Bieber kissing Gomez on a Hawaii beach last year, the "Wizards of Waverly Place" actress initially received death threats via Twitter. But Bieber doesn't seem to have suffered any major career backlash. In the last year, he banked $55 million, according to Forbes.

Bieber and Gomez, like Cyrus and Jonas, are devoutly Christian. Jonas and his brothers famously wore purity rings as teenagers, while at 16 Cyrus proclaimed her intention to remain a virgin until marriage, in keeping with her Christian faith.

Duff, Cyrus, Jonas and Gomez were all born in Texas or Tennessee, and "young adults from the South and those with more religious backgrounds are more likely to marry earlier," according to Bradford Wilcox! , directo! r of the National Marriage Project at the University of Virginia. "There's a stronger cultural religiosity there," Wilcox said. "Even for people who aren't devout, they're embedded in a milieu that tends to view marriage at a young age as socially acceptable."

Even so, the odds for those who marry young are bleak: Roughly 60 percent of couples who marry between 20 and 25 divorce, according to the National Center for Health Statistics. That's likely at least in part because the human brain isn't fully developed until age 25 or 26.

Still, Dr. John Sharp, a faculty member at Harvard Medical School, said stars like Cyrus may not be making a mistake in marrying young. "If the choice is between sowing one's oats and getting into trouble with excesses, then this looks like it could be a healthier choice," he said. "You find someone you trust and hold on to them tight, and maybe you don't have to go through those difficult, dangerous years where people fall prey to substance abuse."