Scarlett Johansson is learning about a painful part of her family’s past.
The actress sat down with Henry Louis Gates, Jr. for an episode of PBS’ Finding Your Roots, in which she examines her mother’s family tree and discovers the unfortunate fate of multiple ancestors in Europe.
In a PEOPLE exclusive sneak peek at Tuesday’s episode, the actress fights back tears as she learns that while her Jewish great-grandfather worked as a grocer in New York City, his brother — along with his family — died in the Warsaw Ghetto during World War II.
The ghetto was “a 1.3-square mile area sealed off from the rest of the city where authorities forced all of the city’s Jewish residents to live. At its peak, more than 400,000 Jews were crammed into the ghetto, living in squalid conditions with insufficient food rations. No more than 20,000 of them survived the Holocaust,” according to PBS.
“Wow, that’s sad,” she says in the clip after reading the family document before she is overcome with emotion. “And I promised myself I wouldn’t cry. But it’s hard not to.”
“I mean, you really couldn’t imagine the horror. It’s just so crazy to imagine. … It’s crazy to imagine that Saul would be on the other side selling bananas on Ludlow Street. And how different it would be being in America at that time,” says Johansson, 32. “The fate of one brother versus the other.”
Although a disheartening discovery, knowing her family history makes Johansson feel more connected to her past.
“It makes me feel more deeply connected to that side of myself, that side of my family,” she says, and adds, “I didn’t expect that.”
In the episode, she will also learn about her father’s Danish roots.
Finding Your Roots with Henry Louis Gates, Jr. airs Tuesdays (8 p.m. ET) on PBS.