Television has “Modern Family,” and now the big screen has Lisa Cholodenko’s new picture, a portrait of unconventional domesticity that toys with tough issues but ultimately settles for friendly familiarity. One can imagine the picture’s premise taking the story into really strong areas, but Cholodenko opts for unthreatening comedy-drama instead. The result is inoffensively amusing, and occasionally touching, but also a little bland.

The family in question is a California foursome consisting of Nic (Annette Bening) and Jules (Julianne Moore), a committed, long-term couple, and their teen children Joni (Mia Wasikowska) and Laser (Josh Hutcherson). The kids are the results of the women’s employment of a single anonymous sperm donor, whose contribution made Nic pregnant with Joni and Jules pregnant with Laser. They’re basically a happy group, with Joni at point of graduating from high school and going off to college, even if Nic, the hard-driving breadwinner, is more than a little bossy and Jules is increasingly dissatisfied with contributing so little.

What really causes turmoil, however, is Laser’s desire to locate his biological father; and now that Joni’s eighteen, she can legally initiate a search. They eventually locate Paul (Mark Ruffalo), a scruffy old-hippie type who grows organic veggies for his trendy little restaurant and rides a motorcycle. The easygoing fellow bonds easily with the kids—he’s instrumental, for instance, in persuading Laser to break with an inappropriate buddy (Eddie Hassell). But Nic is hostile until, over dinner, the find a shared love of Joni Mitchell; and the more accommodating Jules is won over in more ways that one when Paul supports her desire to start a landscaping business by hiring her to redo his overgrown backyard. Unfortunately, at that selfsame Joni Mitchell dinner Nic discovers that her partner has been having more business with Paul than just yard work.

“The Kids Are All Right” tries to make its comedy seem sharper than it actually is by situating it among a fairly sophisticated ensemble of characters, and for a time the picture is a pleasant, if hardly revelatory, portrait of a family that may be atypical but is a basically loving brood with problems one can easily relate to. It certainly helps that the performances are so strong. Bening anchors things with another of the strong-willed but vulnerable characters she began with her turn in “Mother and Child,” Moore does the slightly dotty shtick to perfection, and one couldn’t ask for a more ingratiatingly troublesome interloper than Ruffalo. The kids are alright, too, with Wasikowska overcoming the stiffness she exhibited in Tim Burton’s misguided “Alice in Wonderland” and Hutcherson making Laser convincingly real.

But when the script moves into the relationship between Jules and Paul, it stumbles into uncomfortable farce. We’re suddenly in territory where a scene in which two characters agree never to link up again is followed by one of them in bed after another encounter—the sort of thing that wouldn’t be out of place in the worst Hollywood romantic comedy. (And do we really need yet another sequence built around a shared love of a pop song? One expects that sort of stuff in studio movies, too, but now it’s becoming the cliché of choice in independent films like this one and “Cyrus.” Knock it off.) Things do recover in the final reels, where the relationships are restored after all the trouble, but the damage has been done.

Still, “The Kids Are All Right” has more going for it than not. It offers some genuine insights along with the banalities, and the cast elevate even the low spots to a tolerable level. It looks fine too, with high-class production design (Julie Berghoff) and art direction (James Pearce Connelly), expert cinematography (Igor Jadue-Lillo) and editing (Jeffrey M. Werner), and a typically eclectic background score (the original music by Craig Wedren). The upshot is a movie that might not be great, but is certainly above average.