Hartog was a son of Samuel Mullem and Joanna Salomon van Bever, a family with 9 children. One brother and one sister died before the war. The others, Eva, Salomon, Jacob, Betje, Duifje en Judith did not survive the Holocaust.
Hartog married on 11 Juni 1903 in Amsterdam to Sara Snoek from Den Helder, daughter of Nathan Snoek en Roosje Dupont. Sara passed away already in 1931 and was buried at the …