The Cleavers, the Nelsons, the Andersons, the Williamses, the Stones . . . all those familiar TV neighbors helped to form America's collective fantasy about the Nuclear Family. But apart from their mother-father-sister-brother configurations, they offered few clues about coping with the real problems cropping up outside the small screen.

In Alan Bowne's black-edged comedy "Sharon and Billy," which receives a persuasive and unsettlingly funny East Coast premiere at Woolly Mammoth Theatre, we eavesdrop on a family in a Los Angeles suburb in the early '50s: a Mom and a Dad and two kids in their early teens, looking about as TV-typical as they come.

But squirming beneath the surface are the uncomfortable issues so willfully, skillfully ignored by those antiseptic, black-and-white families: the parents' class; racial and economic insecurities; the confusion of adolescents reaching sexual maturity in close, insular proximity.

A little bit confused and frightened themselves, Sharon and Billy's parents are unwilling -- unable, really -- to give their kids much guidance. So accidents will happen, and in Bowne's play -- a comedy about incest, strange as that may sound -- this nuclear family is in dire danger of meltdown.

For 15 years, Father knew best. But now that his kids are growing up and going out, he's finding it harder to keep his household under control. Precociously budding 15-year-old Sharon arouses paternal ire (and fraternal interest) when she hangs out with the neighborhood hoods. Dad reacts as if his property has been stolen. "I work like a dog to give you all this," he barks, slamming his fist on the dinner table, the arena for every crisis.

Sharon and gawky, brainy Billy are not only dependents, but virtual prisoners -- they can't talk or strike back, there's nowhere else to go, no one to turn to but each other. Their brief, almost accidental, incestuous affair isn't really the focal point here -- it happens in the second scene. The playwright is more concerned with the emotional damage done by the family itself.

Bowne quickly hooks us with laughter, as the opening scene races giddily through a veritable litany of '50s cliche's: Wonder Bread, Miracle Whip, Elvis, etc. But the laughter becomes more uncertain as familiar territory begins to cave in. Bowne ends each of his seven short "episodes" with a loaded line and a fade-to-black, but the play's ending is necessarily unresolved -- life having refused to neaten itself up in time for the curtain call.

Like Bowne, director Howard Shalwitz keeps us off-balance, uncertain whether to laugh or wince, and successfully maintains the play's comic element even as the scenes grow progressively darker. There are fine performances in the title roles by Gra'inne Cassidy and Grover Gardner, both of whom are funny and touching without resorting to condescension or cartoonishness. A scene in which the siblings play exuberantly with their food begins hilariously, then becomes suddenly poignant as the kids act out their frustrations against their father.

Michael Willis puts a believable bitterness behind Dad's regular-Joe exterior. He's a malign Ralph Kramden, a burly, blue-collar tyrant who's infrequent bouts of laughter are especially shudder-provoking. It's harder to get a fix on Karen Hutcheson as Mom -- perhaps because the character as written is a cipher, and Hutcheson plays her, improbably, like Saturday Night Live's "Church Lady."

At first sight, Lewis Folden's set provokes easy laughter, with its stylized '50s iconography. But there's more to it than affectionate parody; the performances are amplified by the culturally barren decor, the punishing-looking metal chairs pulled up to the Formica dinette set, the isolating wooden fence just beyond the sliding glass doors of the box-like family compound.

Sharon and Billy, by Alan Bowne. Directed by Howard Shalwitz; setting, Lewis Folden; lighting, Daniel McLean Wagner; costumes, Rosemary Pardee-Holz; sound, Ric Cooper. With Gra'inne Cassidy, Grover Gardner, Karen Hutcheson, Michael Willis. At Woolly Mammoth Theatre through March 13.