Abraham van Westerborg was a son of Salomon van Westerborg (passed away 13 March 1932) and Antoinette Elizabeth Fles. He married 7 December 1926 in Rijswijk a non-Jewish woman, who has survived the war.

Abraham was born into a family of three children, of whom he and his brother Alex Marcel were killed in the Shoah. His eldest brother survived the Holocaust.

City Archive of Rotterdam, family registration card of Salomon van Westerborg, Municipal Archive of Den Haag, family registration card of Abraham van Westerborg.