LOS ANGELES — The sister act of identical twins Tia and Tamera Mowry has centered on their clean-cut image and bouncy charm. The formula served them well as perky child stars in their ‘90s sitcom “Sister Sister,” their Disney Channel ‘tween vehicle “Twitches” and the more mature “Double Wedding” on Lifetime.

The well-scrubbed image mirrored their off-screen lifestyle. Openly religious, the Mowrys were content to seek more uplifting roles rather than emulate their young peers. The sisters stayed true to their values — no trashy horror movies, sex tapes, battles with eating disorders, kids out of wedlock, club-hopping or revolving-door boyfriends.

It’s a high ground that would seem to have no place in the arena of reality television, where family dysfunction and hysterical, foul-mouthed fights are often the main attraction. But the sisters have bucked that trend with their Style Network reality series “Tia & Tamera,” which in its first season has become the highest-rated program in the cable network’s 12-year history, averaging more than 750,000 viewers per week.

Call them the anti-Kardashians: There is no foul language that has to be bleeped on “Tia & Tamera,” no provocative emphasis on sex.

In the series, which has just been renewed for a second season, the twins display dynamic chemistry tinged with edginess and more than a little competitiveness that leads to sharp conflicts. But unlike other reality shows, they resolve their differences without disintegrating into outrageous or exaggerated behavior.

“With certain reality shows, you actually see bad acting,” Tia said. “If we were going to do that, we’d rather be acting as characters. We know there are other sister shows, but we wanted to be different and more positive.”

Fueling the interest is a wave of nostalgia that has sparked projects from TV personalities such as Fran Drescher and Roseanne Barr. Nick at Nite even launched a block of shows from the 1990s labeled “The ‘90s Are All That,” featuring hits from that era that include “Clarissa Explains It All” and “All That.”

The Style Network reality series follows the 33-year-olds as they confront dramatic life changes — Tamera’s marriage to Fox News correspondent Adam Housley and the married Tia’s first pregnancy. The first season documents how Tamera’s stress in planning her large wedding collided directly with Tia’s preparations for motherhood, with Tia’s physical condition preventing her from being constantly available to her sister.

“I’m very surprised,” said Tamera, referring to the show’s success while relaxing with her sister recently at a Studio City cafe. “We had awesome success with ‘Sister Sister’ and the movies, but we never thought people would be as interested with who we are as people.”

Although the twins say they were caught off-guard by the show’s popularity, Style Network President Salaam Coleman Smith said she expected the show to hit a chord immediately with its young female demographic.

“We went into this with the intention of it being a big hit,” Smith said. “There’s the perfect combination of things — twins, babies and marriage. There’s child stars, so there’s a nostalgia factor. The women who watched ‘Sister, Sister’ as they were growing up are now at the sweet spot of our target audience. They see Tia and Tamera as very relatable. There’s a lot of heart, but at their core they’re dealing with issues a lot of women are dealing with.”

One of the highlights of the season was Tamera’s bachelorette party. She repeatedly asked Tia not to hire strippers. But a stripper was hired by Tia and other friends, upsetting Tamera so much that she started crying after he left. Tia pointed out that Tamera had said she didn’t want “strippers,” not “a stripper,” causing her sister to laugh through her tears.

The sisters, who are executive producers, said they insisted that situations not be set up to heighten conflict. “It was extremely important to us that this be real,” said Tia. “There were times when the producers would approach us with things that were not real. We said no. We want the drama to naturally happen. We are sisters. The drama will happen.”