Ed Miliband has described the importance of his Jewishness to his own identity, saying it is "intertwined" with his Britishness.
In a highly personal article for the New Statesman, the Labour leader said he felt a growing "duty" to discuss the traumatic experiences of his family during the Holocaust.
He said he was "not religious" and that his relationship with his Jewishness was "complex".
But he said it had defined how his family had been treated, his father - the Marxist historian Ralph Miliband - coming to Britain in 1940 to avoid Nazi persecution and his mother in 1947 after spending the Second World War under an assumed name.
"It explains why we came to Britain. I would not be leader of the Labour Party without the trauma of my family history," he wrote.
"For me, my Jewishness and my Britishness are intertwined. My parents defined themselves not by their Jewishness but by their politics. They assimilated into British life outside the Jewish community.
"There was no bar mitzvah, no Jewish youth group; sometimes I feel I missed out."
He said his mother got him interested in Woody Allen films and his father taught him Yiddish phrases.
He said that he and wife Justine broke a glass at their wedding last year.
"My family history often feels distant and far away. Yet the pain of this history is such that I feel a duty to remember, understand and discuss it - a duty that grows, rather than diminishes, over time," he wrote.
"As children we were only dimly aware of it but we caught glimpses. When I was seven, my family went to visit my grandmother in Tel Aviv. Pointing at a black-and-white photograph, I demanded to know who was 'that man in the picture'.
"I remember being taken swiftly out of the room and then being told quietly that he was my grandfather David, who had died in Poland long before I was born.
"It was only some years later that I realised my mum's father had died in a concentration camp, murdered by the Nazis for being Jewish."