At its simplest, The Kids Are All Right is about two teenagers who seek out their sperm-donor father. But really the film is about family—from pretty much every angle you can imagine. The fourth feature from Lisa Cholodenko (High Art, Laurel Canyon) is rich and real, so textured that not a second of its 104 minutes seems superfluous. That it centers on a lesbian couple is, for the most part, as insignificant a detail as an on-screen pairing of a curvy blonde and tall, dark, and handsome man.

Nic (Annette Bening) and Jules (Julianne Moore) met in college and decided to each conceive a child via artificial insemination. Now that Joni (Mia Wasikowska) is 18, her younger brother Laser (Josh Hutcherson) is pushing her to follow through on her legal right to contact their mothers’ baby daddy. Joni’s hesitant but does it anyway, and soon they meet Paul (Mark Ruffalo), the wayward, motorcycle-riding owner of an organic farm and restaurant who says things like, “Right on!” and “I love lesbians!” during the initial phone call.

The siblings go through phases of liking and disliking Paul, who is a bit taken aback but otherwise willing to be a part of their lives. And so do their mothers, who agree to meet him when the kids ’fess up. Nic, a doctor, is the champion of passive-aggressiveness, and the dynamic between the five of them takes a similar tone—a mix of superficial politeness, sarcasm, irritation, and genuine warmth.

The latter comes mostly from Jules, a New Age-y sort who doesn’t follow through on the projects she starts and whose advice to Laser regarding his obnoxious best friend amounts to, “Is he helping you grow?” Her latest venture, a landscaping business, allows her to know Paul better when she does some work at his home. She likes what she sees, much to Nic’s wine-fueled annoyance.

Hardly a note of The Kids Are All Right, which Cholodenko co-wrote with Stuart Blumberg, feels unnatural. (Sitcom-y, perhaps, as when Paul drives Joni home past curfew on his bike.) The inverse of this year’s earlier, ridiculous ruckus over gay actors playing straight characters proves true here: Bening and Moore may be A-listers, but there’s nothing forced about Nic and Jules’ relationship, sexual or otherwise. (Granted, Moore got some practice in her last film, Chloe.) Bening is especially terrific as the Alpha Mom, vocal and cutting even when she’s not guzzling a bottle of red; when Jules gently points out during their lunch with Paul that Nic’s on her fourth glass of wine, the latter retorts, “It’s my third, but thanks for counting!” Moore, meanwhile, provides much of the comic relief, particularly when she tries to explain to Laser why the couple watches gay-male porn, citing the “inauthenticity” of lesbian films that often feature actresses just pretending.

The tumbling consequences of Joni’s initial phone call are largely representative of everyone’s messy family lives. There’s the distance that wedges itself into long-term romance, infidelity, brother-sister relationships, teenage rebellion, leaving the nest, and the difficulty of accepting that the person you spend the most time with is actually a douchebag. Of course, there’s also the central question of anonymous sperm donation and whether it’s wise to allow the children born of this artificial union to get to know their biological fathers. (Joni says she “gets it,” but then follows with: “Like we’re not enough, or something?”) Overall, Cholodenko’s film is about family, traditional or otherwise. And you don’t have to have two moms to relate.