In the innocuously chipper family comedy Cheaper by the Dozen, Steve Martin and Bonnie Hunt represent a new paradigm of two-career sitcom parenthood in a feature-length format: They're sparky gender equals, simultaneously raising their brood of 12 and ogling one another's adult butts to suggest that the two still have a swell sex life and a sense of humor. I wish Martin's Tom and Hunt's Kate would make full use of the comic stars' sardonic specialities. But that ain't scheduled in this sprightly, updated remake of a 1950 movie from a 1948 memoir of growing up in a turn-of-the-century household.
Back then, Papa was an efficiency expert -- how square. Now, Dad's a college football coach, Mom's on a publicity tour for her book (about raising the dozen), and the kids act out with genial rebellion to suit every target audience group and child-development phase. The 12-pack includes ''Coyote Ugly'''s Piper Perabo as adult daughter Nora, ''Smallville'''s Tom Welling as the eldest son, and ''Lizzie McGuire'''s Hilary Duff as a teenager who's, like, sooo ready to star in ''Lizzie McGuire.''
The baker's-dozen bonus, meanwhile, is a coyly uncredited Ashton Kutcher, having a dandy, funny, self-mocking time as Nora's vain, aspiring-actor boyfriend. Director Shawn Levy and much of the ''Cheaper'' team come from the star's 2003 movie ''Just Married''; clearly Kutcher's at home with these dudes, free to pull a ''Punk'd'' -- on himself.