Democratic presidential candidate Bernie Sanders got personal about his Jewish upbringing during an interview with NPR’s “Morning Edtion” on Thursday.

Speaking how the history of the Jewish people had inspired him to oppose the current upsurge in anti-immigrant sentiment and Islamophobia, Sanders – who was in the studio for a lengthy interview – pulled up his sleeve to demonstrate the serial numbers Holocaust survivors had inscribed on their arms.

“When I was a young boy, I can remember in the community that I grew up in, seeing people in the community who had numbers that were on their arms and these were the Nazis’ identification numbers that they put on prisoners in the concentration camps,” he said in the interview. “And I, certainly, was aware of the fact that much of my father’s family was killed in the Holocaust.”

Sanders recalled returning to the Polish town his dad grew up with his brother Larry a couple of years ago. “It was a very traumatic experience for me as a young man to know that my father’s family was killed by Nazis – killed by Hitler,” he stated.

“And that left, if not intellectually, at least an emotional part of me that would say: ׳God, we have got to do everything we can to end this kind of horrific racism and anti-Semitism,׳” Sanders said. “And I’ve spent much of my life to fight that.”