Scarlett Johansson knew that her mother’s side of the family came from Jewish communities in Eastern Europe, but she didn’t know much else about her Jewish ancestors. When the movie star appeared on the PBS show “Finding Your Roots” on Tuesday night, she learned some specifics about those branches of her family tree — and broke down in tears upon learning about their tragic Holocaust experiences.

But it turns out you don’t actually have to be a guest on “Finding Your Roots” to, well, find your roots. After watching the episode, a family spread across in Israel, California and New Jersey found out they were related to Johnasson via those same Eastern European ancestors.

In 1910, Johansson’s maternal great-grandfather Saul Schlamberg (who was then still going by his Yiddish first name, Schlachne) immigrated from a small town in Poland to New York City. He settled on Ludlow Street in the city’s Lower East Side, which was full of Jewish immigrants at the time, and was believed to have sold bananas at a market. He was alone, not yet 25 and very poor.

“You kind of imagine your ancestors, ‘Oh, they came over on this ship or whatever,’” she said. “But then to actually see the paper and know that they were journeying towards what would eventually result in me — it’s pretty surreal.”

Sadly, the narrative takes a dark turn as host Henry Louis Gates, Jr. shifted to the family Saul left behind in Grojec, Poland. Saul’s brother Moishe and his family of 10 children ended up in the Warsaw Ghetto by 1942. By that time, all of Grojec’s Jews had been either killed or deported.

“I cant imagine what you must be feeling,” Johansson says when Gates asks about what she thinks deportation for the family must have been like. “Just hell, it must’ve been hell.”

Thanks to a testimony one of Moishe’s daughters sent years later to the Yad Vashem Holocaust museum in Israel, Johansson learns about the fate of some of Moishe’s other children: Zlata, 15, and Mandil, 17, both died in the Warsaw Ghetto.

Gili Rozenfeld, 29, a video editor who lives in Tel Aviv, caught a glimpse of the episode with Johansson. She was shocked when she recognized the names of Johansson’s relatives, particularly Zlata Szlamberg, who was 15 at the time she died, and Mandil Szlamberg, who was 17. They were her siblings of her grandmother Sara.

Rozenfeld immediately dialed her mom, Dina, in California and her big sister, Michal, in New Jersey and told them to watch the episode.

They did. And like Johansson, they welled up, but not because they discovered a relative who was a big Hollywood star.

“We were overwhelmed that we had any relatives at all,” Michal Rozenfeld told JTA.

On the phone Michal, 42, a designer of children’s clothing who lives in Hoboken, New Jersy, said there was no doubt that the Szlambergs that Johansson read about on screen were her ancestors, too.

“There aren’t many Szlambergs” near Warsaw, Michal said.

Michal and her family grew up hearing stories — and names — from their grandmother.

“She told the entire family how she missed everybody and would like to have had family for the holidays,” Michal said. “We knew that they [Zlata and Mandil] existed. We knew that they died in the ghetto.”

However, “We didn’t know [for sure] that there was any other family,” she added. “We vaguely knew there was a great-grand-uncle who moved to the United States, but we didn’t have anymore information.”

“It’s been an emotional few days. We couldn’t sleep. We were all very happy. I don’t know if it gave us closure,” Michal said, “but it definitely made us happy to discover that there were more of us that we thought.”

Though their great-grandfathers were brothers, Michal and her family have no plans to contact their A-list cousin.

“We don’t want to impose,” she said.