A good rule of thumb for filmmakers is that if you’re going to make a classic movie the foundation of a new one, you’d better be sure the comparisons viewers are going to draw won’t be too odious. It’s a rule that’s seriously violated by Rob Reiner’s “Rumor Has It…” The premise of T.M. Griffin’s script is a clever one–a just-engaged young woman discovers that her California family provided the basis for the novel from which “The Graduate” was adapted, and she begins to suspect that the fellow her mother briefly ran off with before returning to marry her dad might be her biological father (as well as having slept with her grandmother!). True, in addition to being the sort of idea that will appeal especially to movie buffs, it’s also a little creepy. But if executed smartly, it could still work.

Unhappily, it’s not, and it doesn’t. The set-up has high-strung Sarah Huttinger (Jennifer Aniston) returning from New York to her Pasadena home, with cute-as-a-button fiancé Jeff Daly (Mark Ruffalo) in tow, for the wedding of her bouncy sister Angie (Mena Suvari). She’s always been troubled by the fact that she’s so different from both Angie and her down-to-earth, long-widowed dad Earl (Richard Jenkins), and in the course of the festivities she becomes aware not only that she was actually born a bit shy of nine months from her parents’ wedding but that there’s a persistent rumor in the neighborhood that the book “The Graduate” was actually a roman à clef that disguised a real occurrence in some local family. This leads her to confront her hard-bitten maternal grandmother (Shirley MacLaine), who eventually confirms that she had slept with one of her late mom’s boyfriends, and that her mother had in fact disappeared briefly prior to her wedding, before returning to marry Earl. Now certain that the mysterious Lothario is her real father, Sarah tracks him down; he turns out to be rich, handsome Beau Burroughs (Kevin Costner), who’s still quite the ladies’ man. Complications necessarily follow–some of them, if one bothers to think about things too closely, more than a bit icky–but the most important fallout involves a possible split between Sarah and Jeff, since her involvement with Beau merely brings to the fore the doubts that she (just like her mother before her) harbors over her impending nuptials.

It’s possible that some viewers will take to the mildly risque but generally sweet and eventually syrupy goings-on in “Rumor Has It…,” and there certainly are amusing bits and pieces. MacLaine steals virtually every scene she’s in with her harridan manner and acerbic wisecracks–she really seems to enough playing a tough old broad–and both Jenkins (who seems to be in every second movie released this year–his agent needs to be more selective) and Suvari carry off their big scenes (a tearful revelation and a frantic anxiety attack, respectively) well enough, even if the sequences themselves aren’t terribly well-written. But Costner’s worldly confidence, which passes with breathtaking speed from the avuncular to the romantic, has an unsettling undercurrent to it, and Ruffalo has played the accommodating schlub of a boyfriend entirely too often of late–it’s really time that this fine young actor got the chance to sink his teeth into a challenging role again. The picture’s major problem, however, is Aniston, whose performance is so incessantly busy that she seems never to miss an opportunity to turn up a brow, bite a lip, roll her eyes, frown in that “Friends”-like way, pout or otherwise fidget. She’s such a whirlwind of fussiness that she makes everyone around her, however hard they’re trying, look almost stationary by comparison. The failure to rein her in is only one facet of Reiner’s failed direction, which otherwise lets the picture lope along in a comfortable fashion intended, one supposes, to be easygoing but coming across as flaccid. The movie looks fine–production designer Tom Sanders and art director Thomas P. Wilkins have arranged for stylish settings, and D.P. Peter Deming makes good use of both the urban backgrounds and the sometimes lovely seaside and rustic locations. But the glossiness they provide can’t disguise the emptiness of the package. As for Marc Shaiman’s score, it’s so bland and ordinary that it barely registers at all.

Overall “Rumor Has It…,” in fact, is so pedestrian it almost makes one regret Rob Reiner’s decision not to run for governor of California. The absence of Arnold Schwarzenegger from the screen over the past year has been a blessing, and it would have been doubled had Reiner abandoned the director’s chair for awhile, too.