The joke’s on us? It turns out “Curb Your Enthusiasm” actor Larry David and politician Bernie Sanders are related — distantly related, that is.

David uncovered his connection to Sanders while filming an upcoming episode of PBS’ “Finding Your Roots," the network confirmed. The newly found relatives appear completely shocked in the new season's trailer.

"You're kidding!" Sanders says, slapping his palm to his forehead as he's told about the connection. Their episode will kick-off season 4 when it airs on Oct. 3 at 8 p.m.

David first discussed the revelation Wednesday at a Television Critics Association press tour panel discussion for his HBO series, returning for a ninth season in October after a six-year hiatus.

“I was very happy about that,” David said about finding out he’s related to Sanders, who's been long considered his doppelgänger. “I thought there might have been some connection.” Both Sanders and David were born in Brooklyn in the 1940s. The “Finding Your Roots” episode reportedly takes David and Sanders back to the borough for the discovery. Sanders and David trace their connection back to Jewish communities in Eastern Europe.

People have been comparing David to Sanders together for years — and it isn’t just because of his spot-on “Saturday Night Live” impressions that began in 2015 when Sanders was running for president. With strikingly similar facial features, the two even swapped roles and played each other in a “Saturday Night Live” sketch, “Steam Ship,” in February 2016.

“Finding Your Roots” hosted by Henry Louis Gates, Jr., takes celebrities on a hunt to discover the secrets hidden in their family trees. Mia Farrow, Bill Maher, Bill O’Reilly and Maya Rudolph are just a few of the celebrities who appeared on previous seasons. This year's full celebrity lineup, which also features Amy Schumer and Scarlett Johansson, has not yet been announced.