Jacob Fles was a son of Hijman Fles and Rika Fles. He married Betje Grootkerk on 8 September 1920 in Amsterdam, a daughter of Mozes Grootkerk and Sara Calo.
Jacob came from a family with 12 children, of whom three children have died already at young age. His other siblings were Isaac, Emanuel, Lea, Gracia, Sara, Benjamin, Levie and Elisabeth.
City Archive of Amsterdam, family registration card of …