You pick up on a big drawback to the Seth Rogen comedy “An American Pickle” the first time he shows up in two guises on the screen. Here’s a movie that abandons most everything that makes Rogen special in its very conception.

A near legendary and legendarily profane and pot-friendly riffer and comic reactor, Rogen plays opposite himself in most of the scenes in this daft but DOA fantasy. Neither Seth has much that’s funny to say or do, and Rogen apparently couldn’t goose the performances or the dialogue to make anything better happen.

He’s no damn good playing off himself.

The pitch was promising enough. A ditch-digger and shtetl survivor — think Tevye from “Fiddler” but without the singing or dancing — woos and marries Sarah (Sarah Snook) and after one Cossack pogrom too many, escapes with her to 1920 New York.

Herschel (Rogen) takes a job smashing rats in a pickle factory, and dreams not just of affording seltzer water, but of a day “100 years from now,” when his descendants have ascended the ladder of prosperity and the name “Greenbaum” will be “biggest in all of America.”

He even buys a big cemetery plot against that day, and to ensure that family and legacy and Judaism remain the driving force of their descendants.

Damned if he doesn’t fall into a pickling vat the day the factory is condemned, only to be released and revived 100 years later. A scientist (Sean Whalen) explains “how” in a press conference, which narrating Herschel wisely summarizes without detail, “hees logeek satisfying everyone.”

Herschel meets his one living descendant, great grandson Ben (Rogen again) is a “freelance mobile app developer” whose “conscientious shopping app,” BoopBop, isn’t quite ready to sell. His job becomes, for a while, to explain the changes in the world, America and Brooklyn to bearded relic Herschel.

“Interracial couple,” Ben says to Herschel’s surprise, “totally cool now…in parts of the country.”

In formula terms, this Simon Rich script is a “fish out of water” comedy, in this case, about a Greenbaum out of brine. Take the stranger in this strange land, introduce him to the “organic” (over-priced) markets, Williamsburg (NY) metrosexuals, Prius taxis and Twitter. Let the hilarity ensue.

It never does.

Rich’s script avoids taking the easy route and instead sets us up for an endless succession of not-that-funny scenarios that grope around for a payoff.

Herschel feuds with Ben over Ben’s agnosticism, Ben’s timidity about selling his app or keeping up the family cemetery. He blanches at the over-priced produce and starts making “artisanal” pickles out of dumpster produce, discarded jars and salt and genuine New York city “rainwater.” He goes “viral” in the process.

Ben? His only purpose becomes foiling his backward great grandfather’s enterprise.

On the page, there’s a little “find your heritage” arc to Ben’s story, and that’s it. There’s precious little “growth” for Herschel, even though the mild shock of hearing Rogen speaking Yiddish and tossing around how “Hashem” has blessed Herschel in this way or that one is a novelty.

And there is literally no other character given any chance of making so much as an impression. What, did they pay Rogen twice and not have the cash for co-stars, actors who would require meatier roles from the screenplay?

I counted maybe three laughs in the thing, and one is an after-the-credits scene and involves a recent Rogen co-star and Jewish showbiz legend. Another?  Herschel narrates about how much he and his Sarah have in common.

“Her family was murdered by Cossacks, MY family was murdered by Cossacks!”

Rogen vs. Rogen is roughly half as amusing as the least amusing Rogen character ever. And the “rediscover your heritage and traditions” stuff isn’t original enough to make it past a table read for “The Goldbergs.”

Nice period detail, a few cute situations, one half-interesting character and three laughs, that’s the pickle this picture puts itself in.

MPAA Rating: PG-13 for some language and rude humor

Cast: Seth Rogen, Sarah Snook, Jorma Taccone, Carol Leifer

Credits: Directed by Brandon Trost, script by Simon Rich, based on his short story. An HBO Max release.

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