“A baby doesn’t know how rich its parents are,” Dustin Hoffman famously said in defense of the most expensive flop of his career, the comedy “Ishtar.”

That aphorism could cover pretty much any movie you sit down to watch. We don’t need to know how it was made, how much it cost, how much a movie needs to earn and how many actors/writers/directors were hired, considered, fired or quit.

All that matters is what’s on the screen.

If there’s an exception to this “knowing too much” rule (admittedly, one not everybody is as zealous about as me), it might be “Keep the Change,” a New York romance with a big, fat twist.

Many of the characters are on the autism spectrum, with varying degrees of socialization and intelligence. And many of them are played by people whose symptoms mirror those of their characters, turning our attention away from the disability and onto the obstacles to romance within this community and the myths we and culture have attached to folks like this.

David (Brandon Polansky) comes from money. We meet him in the back of a limo. He’s sure he’s hilarious, and shares his tactless jokes with one and all, including his driver.

“Why did the bum vote for Obama? He wanted CHANGE!”

It isn’t clear right away, but there’s something a little off about this guy, who looks a little like Mark Ruffalo and acts a lot like a fighter who’s taken a few too many shots to the head. He wears sunglasses constantly. He prowls dating websites, smothers would-be dates with his version of oily charm, and only scares them off when one of his many, many jokes finally crosses the line. Cracks comparing summer camp to “Death Camps” in the Holocaust will get you in trouble with the Tribe every time.

When he’s dropped off without ceremony at a Jewish Community Center for a court ordered group therapy session, he may say “I don’t have a problem. I’m just passing through.” We know better. So do the more overtly Asperger’s sufferers and autistic adults there. David may play on his phone and reject interaction. But he belongs here.

Writer-director Rachel Israel’s film gives us permission to laugh, not so much at the awkwardness of one and all — limited eye contact (wearing sunglasses gives David a crutch for this), tactless bluntness — as at the ways a society like this might function. There are plenty of ruffled feathers, trumped by a generous helping of forgiveness.

Aspiring dramaturge Sammy (Nicky Gottlieb) would love David for his new play, a role he was born for, a gay man.

“I’m not gay!”

“But you have such gay mannerisms!”

Oh well, never mind. Bygones, etc.

It’s in this closed circle that David finally finds a woman who gushes about how sexy he is, who finds him “normal.” Sarah (Samantha Elisofon, an utter delight) is sexy in that Amy Schumer way. She’s plump, confident, assertive and prone to breaking into song at every opportunity, onstage or off.

The first time we hear her, we realize that’s not the best idea. But not Sarah. She just charges on. And David, who struggles to maintain a cocksure air, is simply blown away. Others have to tell him, “Oh, she’s a PLAYA. She just wants you for dates and sex.”

As if that’s a deal-breaker.

The struggle Israel underlines in this genial comedy is within David himself. His parents (Jessica Walter, Tibor Feldman) rein him in, try to keep tabs on his boundaries and emphasize the “normal” in him. Others in that group take him more at face value.

He’s a bit of a jerk, but he’s not close to being the biggest jerk in the bunch. If you thought people with Asperger’s were tactless purely by accident, “Keep the Change” will deflate that myth.

David doesn’t pick up the social signals that his “Muslim sex doll — it blows itself up” joke isn’t appropriate. He literally cannot read the room. And it’s cute that the born comedian — who dreams of making a movie based on his old home movies of the Bar Mitvah and prom he went to when his parents were sure he was more “normal” —  blows his punchline by emphasizing the wrong word.

Other elements of the story are melodramatic tropes — the relative who’s a Broadway star, a first-ever trip on a bus, autistic fish out-of-water at an absurdly expensive fine-dining establishment.

But after all these years of movies and TV giving us Amanda Plummer or Hugh Dancy or that “Rain Man” himself, Dustin Hoffman, pretending to be “on the spectrum,” “Change” finds humanity, a sweet moment or two (rare) and some good-natured laughs at the misperceptions and misunderstandings that occur when on-the-spectrum meets off-the-spectrum, and even among people all on the same wavelength.

MPAA Rating: unrated, with adult themes, sexuality

Cast: Brandon Polansky, Samantha Elisofon, Nicky Gottlieb, Jessica Walter

Credits: Written and directed by Rachel Israel. A Kino Lorber release.

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