“The Kids Are All Right” is an odd little film to find in the middle of an overstimulated Hollywood summer. Heartfelt and funny, the film is like a cool shower on an oppressively hot day — refreshing and invigorating, the sort of unexpected surprise that catches you off guard and sticks with you for days.

Nic (Annette Bening) and Jules (Julianne Moore) preside over a modern American family. Both women have children, biological half-siblings from the same anonymous sperm donor, chosen, we are told, because of his stellar profile.

Though teenagers Joni and Laser (Mia Wasikowska and Josh Hutcherson) love their moms, they are curious about their biological father and, without informing their parents, manage to track down Paul (Mark Ruffalo), a scruffy, free-spirited organic farmer and restaurateur.

The kids come to enjoy Paul’s easygoing personality and man’s man lifestyle, something that is lacking at home. Despite its warmth and obvious nurturing atmosphere, home is a bit suffocating. The reverse is also true — in the kids he never knew he had, Paul finds a sudden jolt of appealing responsibility and a stability his swinging bachelorhood lacked. As everyone wrestles with new and unexpected shifts in identity, they find their current, comfortable and established bonds tested … and possibly broken.

“The Kids Are All Right” is far, far funnier than you might expect. In fact, the film stops just short of becoming a full-fledged comedy, preferring instead to exist in both worlds, flitting back and forth as required. This hybridity, an effective stew of comic surprise and poignant emotional truth, offers a portrait of marriage that is rich, nuanced and, above all, honest.

Despite its title, “The Kids Are All Right” is much more about the parents than the kids. Early on, you completely forget you are watching a married lesbian couple and see them simply as a married couple, facing the same joys and triumphs, ecstasies and monotonies that you and I face in our own relationships.

There is nothing special about Nic and Jules’ relationship except that it is theirs, and to them it is magical. And heartbreaking. There is no attempt to glamorize or embellish their lesbianism (one might argue, in fact, that the film introduces elements that actually — if unintentionally — undermine it). This is a movie involving homosexuality that isn’t about homosexuality.

The film may be sympathetic with their union, but it is not afraid to show it as the flawed and messy collision of human personalities that all marriages ultimately are.

Nothing is as wonderful or as wretched as family. It remains the singular human connection within which joy and agony are willing bedfellows and those we love are just as often those we loathe.

Director Lisa Cholodenko and co-writer Stuart Blumberg understand this implicitly, and have crafted a story of connections made and connections gone awry with wit, warmth and wisdom. “The Kids Are All Right” is one of the year’s most honest, endearing and authentic films.

THE KIDS ARE ALL RIGHT

Cast: Annette Bening, Julianne Moore, Mark Ruffalo, Mia Wasikowska, Josh Hutcherson

Director: Lisa Cholodenko

Theaters: Kimball’s, Cinemark

Rated: R (for strong sexual content, nudity, language, and some teen drug and alcohol use)

Running Time: 1 hour, 44 minutes

Something else: Before a screening of “The Kids Are All Right,” Kimball’s will host a California Wine Tasting at 6:30-7:30 p.m. Friday and Saturday. Cost is $25 per person, purchased at the wine bar.

Photo by 2010 Suzanne Tenner / Focus Features