Gail Shister | 'Brothers and Sisters' is an Olin-Wettig family business

For

Ken Olin

, ABC's

Brothers & Sisters

is more like

Son & Daughter & Wife

.

Olin, co-executive producer of the hit freshman drama, has made it a true family affair. His son, Cliff, 23, is a staff writer. His daughter, Roxy, 21, did a three-episode arc.

And his wife, Patricia Wettig, also mother to the above-mentioned sibs, is a cast regular.

Nepotism? You bet.

"Lucky for me, nepotism is so productive," says Olin, 52, a 1976 Penn grad with a degree in English. Adds Wettig: "It's ridiculous. It's a family business, but it never set out to be."

Olin and Wettig, 55, were costars on the late, great thirtysomething (1987-91) and have worked together on numerous projects. Married 25 years, they met when they were doing a play.

He says: "When you have somebody like Patty, nepotism works in the other direction." Fox had to release Wettig from Prison Break before she could sign on with B & S, according to Olin.

She says: "We've always worked together. It's so much a part of how we do things, we don't see it as peculiar. I would expect some whispers [from jealous actors], but I don't know that I care that much."

As for the kids, Cliff was a writer's assistant on Alias (Dad was exec producer) and has written two B & S episodes. Roxy is studying acting. "I'm really proud of them," Olin says. "They work really hard at what they do."

Wettig says it was almost inevitable that their children would get into showbiz.

"We've always brought our work home," says Wettig, who has a sister, Phyllis Yester, in Downingtown. "Also, it's one of those professions that's hard to resist, a little bit."

As a couple, "we've had decent careers and we've been happy, for the most, as actors and directors and writers," Wettig adds.

B & S revolves around the trials, tribulations and couplings of the Walker family, a constellation of Californians that includes matriarch Nora, a recent widow; and her five grown children.

The cast is sterling, particularly Sally Field as mom and Ally McBeal's Calista Flockhart and Six Feet Under's Rachel Griffiths as her daughters. Field replaced Betty Buckley in the problem-filled pilot. It wasn't re-shot until ABC had green-lighted the show for the fall.

"From a chemistry point of view, it just didn't work" with Buckley and the rest of the cast, Olin says.

"There's nothing about making a pilot that's relaxing. Everything is so pressured, so intense. You're spending an enormous amount of money on a flier, basically. All pilots are troubled, to some extent. Because we have such a high-profile cast, we were under the bell jar in a way I think was probably unfair."

In a part specifically written for her, Wettig plays Holly, longtime mistress to Papa Walker (Tom Skerritt) - who died in the first episode - and mother to a college-age daughter with his DNA.

Holly's existence isn't discovered until the will is read. She immediately alienates the Walkers by interjecting herself into the family business. Her child (Emily Van Camp of Everwood) first appeared on the Feb. 18 episode.

Playing such an unsympathetic character "is a very difficult mountain to climb," says Wettig. "I'm seen as Sally Field's nemesis.

"There's an absolute prejudice against 'the other woman.' What I've gotten from a lot of people is that they're starting to have sympathy for the character in spite of themselves."

In her three episodes, Roxy played the clueless girlfriend of bisexual hunk Chad (former Sex and the City boy toy Jason Lewis), object of Kevin Walker's (Matthew Rhys) desire.

Servicing such a large ensemble cast is challenging, Olin says, but the attraction in a pure drama is that "you have so many places to go. You can't cut to a car chase or courtroom or E.R."

B & S is a lock for the fall. If Olin's just-shot pilot is picked up, he'll have two series on ABC next season.

Eli Stone is about a successful San Francisco lawyer (Jonny Lee Miller, Angelina Jolie's ex) who thinks he's a prophet when he starts having visions. Natasha Henstridge (Commander in Chief) and Alias alum Victor Garber costar.

P.S. If you're worried about more Olins on the B & S payroll, don't be. "We have no more children," says Wettig. "Eventually, we'll hit bottom."