American Jewish comedienne Chelsea Handler realized her family history was no laughing matter last week as she underwent a journey of self-discovery in an episode of TLC’s Who Do You Think You Are, which was aired Tuesday.

In the episode, Handler, who was raised Jewish by her Jewish mother and non-Jewish father, confronted the dark secret her “very, very big, strong” German grandfather, Karl Stoecker, had avoided discussing for years — his Nazi past and role in the Holocaust.

“My German grandma definitely spoke about her life during the war way more than my grandfather did,” said Handler. “He never spoke about it.”

The 38-year-old comedienne discovered during the episode that before immigrating to the United States, her grandfather had been interned in a POW camp for years, probably in Montana. Prior to that, discovered Handler, he’d served as a Nazi soldier in Hitler’s army during World War II.

“When he went back to Germany, he was very eager to come and take his family and move them back to the United States,” said Handler.

Handler, who was raised in New Jersey, became emotional and broke down during the episode as she struggled to reconcile her Jewish upbringing to her grandfather’s Nazi past.

“My grandfather served in the Second World War as a soldier. Whether or not he agreed with Hitler, he was serving in the Germany army,” she said.

“My father, I guess, made a deal with my mother when they had children that they were gonna be raised Jewish. So I connect with my Judaism, or the Jewish side of my family, more than anything else.”