Midway through “Harbor,” Chad Beguelin’s uneven but ultimately rewarding comedy at Primary Stages,  Ted is boasting about his boyfriend Kevin to Kevin’s 15-year-old niece.

“A few years after we met, he actually got published in the New Yorker.”

“Whoa? Uncle Kevin?”

“It was actually a cartoon,” Ted eventually admits – and then explains further: It was actually the caption to a cartoon; Kevin won one of the weekly caption-writing contests.

In truth, Kevin (Randy Harrison) has never written anything, although he’s called himself a writer for a decade. Still, he and Ted (Paul Anthony Stewart) have a nice life together in a big house in Sag Harbor, a life considerably happier than that of his sister Donna (Erin Cummings), a single mother who lives in a van with her 15-year-old daughter Lottie (Alexis Molnar). Donna is pregnant again, but this time she has a scheme; she will give the child to Kevin and Ted to raise. They don’t know it yet.

The set-up evokes such television shows as “Modern Family” or “The New Normal” or, for that matter, “Queer As Folk,” the series for which Randy Harrison is still best-known.

But like the gag in the play about Kevin’s contribution to The New Yorker Magazine,  “Harbor” can’t lay full claim to the tone or quality of any of these shows. The play’s humor is too often closer to that of “Two and a Half Men.”  At one point Lottie says to her mother: “Every guy you ever dated is an asshole. I’ve seen so many assholes, I could be a proctologist.”

“Harbor” has too many cheap lines like that, which are not as clever nor as funny as they are supposed to be, and feel imposed by the writer, rather than springing from the characters.

Indeed, the characters themselves initially seem too obviously drawn: Donna is uneducated and crude, more a child than her daughter Lottie, who is sensible and well-read, the real parent in the relationship.

Yet, despite its bouts of glibness, “Harbor” proves by final curtain to be a worthwhile entertainment.

Director Mark Lamos has assembled a first-rate cast. Two of the four actors have experience on television: Besides Randy Harrison, Erin Cummings was in “Made in Jersey” and “Spartacus: Blood and Sand.” Yet all four performers avoid the kind of mugging delivery that the worst of Beguelin’s lines might seem to encourage. They stay in character, and, by doing so, add depth to the people they’re portraying. Cummins surely deserves credit for turning a cartoon mother into a largely credible human being,  both Harrison and Stewart are reliable and believable, but the stand-out here is Alexis Molnar, who actually looks and acts like a teenager, complete with mercurial swings between contempt, confidence, and insecurity.

Beguelin wrote the book and lyrics for the Broadway musical “The Wedding Singer” and the lyrics for “Elf,” and has been hired to write the book for the forthcoming musical “Aladdin.” He has said that “Harbor,” his first non-musical play, came about because he and his long-time lover felt “pressured” by friends and relatives to adopt a child, but realized they did not want to.

Perhaps this explains the unexpected turns in Beguelin’s script, moments that in their unpredictability somehow put the fate of the characters back in their hands, where it belongs.

It helps that the issues in “Harbor” could not be more topical. “These days I rarely meet a gay couple who aren’t raising children,”  Harvey Fierstein wrote recently in a powerful essay exposing Russia’s “war on homosexuals.”  A new law in Russian forbids the adoption of Russian-born children in any country where marriage equality exists in any form — which means, of course, among many other countries, the United States.

At its best, “Harbor” reflects the kind of personal experience that forces contemplation about what it means to be family.

Click to see photos enlarged

Harbor

Primary Stages at 59E59 Theater

Written by Chad Beguelin

Directed by Mark Lamos

Scenic design by Andrew Jackness, costume design by Candice Donnelly, lighting design by Japhy Weideman and original music and sound design by John Gromada.

Cast: Erin Cummings, Randy Harrison, Alexis Molnar, Paul Anthony Stewart

Running time: 2 hours, including a 15-minute intermission

Tickets: $70

Runs through September 8