'20/20' Talks to Stars and Their Siblings

In some cases, stardom seems to run in the family. From David and Shaun Cassidy, to today's successes Jessica and Ashlee Simpson, Hollywood has a long line of celebrity siblings.

Watch 20/20's full report during a two-hour special Friday at 9 pm.

Whether or not a family becomes a showbiz clan fame can take a toll on relations. Here's a glimpse at how some families handled a rise to the top.

Featured Families: Star Jones | David Cassidy | Hillary and Haylie Duff | Michael Jordan | Aaron and Nick Carter

Pop star Jessica Simpson is a virtual brand name. She has a reality show, a recording career, fast-food endorsements and a network variety show as well. And if she's a brand, the latest brand extension is her sister, 19-year-old Ashlee Simpson.

Ashlee already has a role on the WB series 7th heaven and an MTV reality show of her own on the way chronicling the production of her first CD.

"I always say that Ashlee's not following in my footsteps, she's making footsteps of her own — because she's not becoming me by any means," Jessica Simpson told 20/20.

She may be different, but their father knows that Ashlee's career has benefited from years of his efforts on Jessica's behalf. "The beauty of what's happened here, is that you don't have to knock down the doors that we've spent years knocking down to get in," said Joe Simpson.

And as the two tackle Hollywood there remains plenty of love between the sisters. According to Ashlee they "never had, like, a real fight."

"No it's, it's always stupid stuff," said Jessica. "Like if she takes all my makeup and all my clothes."

When Jessica's career began to take off, the family was strained, so they decided to move to Los Angeles to be together where she was recording her album. "With the Hollywood stories that — you know — Hollywood breaks up the family … in our case I think it saved our family," said Joe.

And the family pitched in again a few years ago, when it was time for Jessica to hit the road on tour. Ashlee had always excelled in ballet so the then 14-year-old traded in her tutu to become a backup dancer for her big sister who enjoyed having her around.

Jessica described her sister as someone who, "can have such a great personality and have everybody be in love with her, every guy lined around the corner."

"[Jessica's] so there for me," said Ashlee in response. "So there for me, and so is my parents."

Big Sis Star Jones

Viewers of a certain talk show know Star Jones as the outrageously opinionated daytime diva: Sharp, flamboyant and ready to try almost anything on television.

Her younger sister, a travel agent and mother of two, told 20/20 Star has always been a bit of a diva. "Always in the mirror," said Sheila Jones. "You know, combing the hair, putting on the makeup, the long nails, the high heels."

Like a lot of younger siblings, Sheila is happy to disclose the less flattering details of her sister, describing her also as "stuck up" and "bossy."

The two are four years apart, and while their mother liked to dress them in different colors of the same outfits, the Jones daughters could not have been more different. They are close now, but say they didn't like each other while growing up.

Star said they didn't get along because they were so different.

"Sheila, in all honesty, was everything I wished I could be," said Star. "She was outgoing. Um, very popular with the boys … Sheila had friends all over the place. And everybody adored her."

The pair sound like typical siblings and favored bickering to getting along until there was a family crisis. "I trace it back to when our mother, was sick with cancer. She's now a 15-year survivor," said Star. "When there was a chance that my mother would not beat that disease, I think Sheila and I somehow thought we had to be together. And we started really working on our relationship."

The sisters became even closer when Sheila had the first of her two boys. Star is kind of an Auntie Mame for all her family these days, but despite her glamorous life and fame, her sister insists she has not "an ounce" of jealousy.

"I would not do what she does for all the money in the world," said Sheila. As it turns out, Star is the one with the envy. "It's funny. People always think Sheila should envy my life … I always envy her life," said Star. "I see the joy that her boys bring her."

Partridge Parade

Can being a teen heartthrob run in the family?

It does if your last name is Cassidy. When The Partridge Family star David Cassidy gave up his idol crown in the mid-1970s, the teen machine sought to replace him with his half-brother, Shaun Cassidy.

David Cassidy told ABCNEWS he was not surprised Shaun was interested in following his lead. "How could he not be?" said David. "It seems real attractive when your older brother's you know, 20 and you're like 15 … everybody's talking about him and everybody's playing his records and buying his stuff. You want to do that, of course."

So Shaun took a role on the Hardy Boys, scored a handful of hit singles and was marketed as the next Cassidy pop-idol. And with a half-brother in the business when Shaun had career struggles, he had someone to turn to for support.

"We were able to talk a lot about, because I'd already been through years of it," said David. "He realized that he was stuck in this TV show and he had to make these kinds of records, and creatively felt very stifled."

Shaun would later step behind the camera to become a respected TV producer and David is still in music, with a tour planned for this summer. What's their secret to sibling serenity? David said it's a matter of remaining supportive: "Can you find happiness in having a relationship, with your family, with your sibling, can you appreciate the fact that their fame … and their success is a good thing?"

Hillary and Haylie Duff

What happens when the younger sibling becomes the bigger star?

That's the case with the now-famous Hillary Duff and her big sister Haylie who was the first to take acting classes. "I thought it was the dumbest idea at first, like when I was younger, because I was such a tomboy, and, like, when Haylie started taking acting classes, I was like, what is that? That's so stupid, you know?" Hillary Duff told 20/20.

She's certainly changed her mind. Hillary now has hit the teen-queen trifecta: on television with the series Lizzie Maguire, in the theatres with two hit films, and on the charts with her No. 1 CD Metamorphosis. All that success could have been tough on an older sister with showbiz dreams, but for these sisters the success is not a strain.

"We never really thought about it before!" said Haylie.

Hillary is confident her sister will succeed in show business as well and said, "It's just a matter of timing."

In fact, Haylie Duff, 19, has been working in edgy independent films, like this summer's Napoleon Dynamite and has begun recording her own CD. Though she sings with her sis on the soundtrack to Hilary's next movie, A Cinderella Story, Haylie turned down an offer to act in the film.

"It's not that I didn't want to be seen as Hilary's sister, because I'm very proud to be her sister — I know how talented she is and I know that I'm talented too. And I never wanted it to look like we used her talent to get me to where I wanted to be," said Haylie.

And while Hilary supports her big sister's aspirations, Haylie's watching out for her kid sister as well. "Haylie has my back all the time," said Hillary who then told her sister: "We're so close … I wouldn't know what to do without you."

Family Feud

Everybody loves Michael Jordan, and they've put him up on a pedestal, except for one of his four sisters and brothers, Deloris.

She says success changed Michael and not for the better. "I saw things happening within my family and a lot of it was the result of his success," said Deloris Jordan.

She claims her kid brother belittled and disrespected her and didn't always share his success with her — at least not as much as she thinks he should have.

Author and sibling expert Dalton Conley explained at the heart of many sibling rivalries is simple economics. "You can't have a dog eat dog world of competitive capitalists out there and expect completely different dynamic inside the home. The family home is not a level playing field itself."

Deloris may have no qualms about going public with her sibling feud —— but her brother apparently does. Michael Jordan declined comment about his sister.

Boy Band Brothers

Fame can split apart more than just siblings. For blond Backstreet Boy Nick Carter and his younger brother, fellow pop star Aaron Carter, their fame took a toll on their family.

Their mom, Jane Carter, was a champion for their careers. She was always their biggest booster sending them to voice and dance classes, driving them to countless auditions only to lose her way in the tumult of showbiz success.

"I saw the change, in her," said Aaron Carter. "She was becoming a different person, pretty much, to me … all she really worried about was the business."

His brother Nick agreed and explained he eventually had to confront his mother and asked for more independence. When he decided to then bring his dad on tour, his mom headed out with Aaron but grew estranged from her husband. The two have since divorced and while they have joint custody of Aaron, he lives with their father.

The boys are now moving forward in their careers. Nick is recording a new Backstreet Boys CD and auditioning for acting jobs, Aaron is set to film a movie this summer while both are navigating the perils and pleasures of dating in the fast lane.

"Honestly, I love, I love … Paris [Hilton] to death, I think she's, she's a wonderful, wonderful human being," said Nick. His brother Aaron jokingly said "good luck," after dating his share of teen stars including Hillary Duff and Lindsay Lohan, "no more celebrity for me. Sorry."

Their mother, Jane Carter, is no longer a part of their professional lives, but her two sons say they still care for their mom. As Nick puts it, "she's always going to be our mother."

Aaron said his relationship with his mom is "fine" and he has plans to spend some time with her to make sure she's doing OK. He added, he would "drop the business in a heartbeat" if anything ever happened to his family.

"I'm always going to love her. I don't agree with all the things that she does sometimes, but that's just me and [those are] my opinions," said Aaron.

The family strife has made him and his brother a lot closer. While Nick said he'll always make sure his younger brother "doesn't get in trouble," Aaron said he also has his brother's best interests in mind.

"My main goal, too, for, for him is to always make sure that he is always on top, and is always very liked and very famous," said Aaron. "I will let him do that before me, you know? I'll put him in front of me always."