Gad grew up in Berlin. His father was a Jewish immigrant from Austria. Gad's mother had converted to Judaism. The Becks lived in a poor section of Berlin, populated predominantly by Jewish immigrants from eastern Europe. When Gad and his twin sister, Miriam, were 5, the Becks moved to the Weissensee district of Berlin, where Gad entered primary school.
1933-39: I was just 10 when the Nazis came to power. As one of a small number of Jewish pupils in my school, I quickly became the target of antisemitic comments: "Can I sit somewhere else, not next to Gad? He has such stinking Jewish feet." In 1934 my parents enrolled me in a Jewish school, but I had to quit school when I was 12 as they could no longer afford the tuition. I found work as a shop assistant.
1940-44: As the child of a mixed marriage [Mischlinge], I was not deported to the east when other German Jews were. I remained in Berlin where I became involved in the underground, helping Jews to escape to Switzerland. As a homosexual, I was able to turn to my trusted non-Jewish, homosexual acquaintances to help supply food and hiding places. In early 1945 a Jewish spy for the Gestapo betrayed me and a number of my underground friends. I was interned in a Jewish transit camp in Berlin.
After the war, Gad helped organize the immigration of Jewish survivors to Palestine. In 1947 he left for Palestine, and returned to Berlin in 1979.