Jacob de Jong was a son of Abraham de Jong and Maaike Cohen. He married 20 October 1920 in Amsterdam to Roosje Naarden, a daughter of Jochem Naarden and Rachel Waas.
His siblings, who did not survive the Holocaust too were Hartog, Marianne, Benjamin, Anna, Wolf, Karel, Rosa and Esther. Two brothers…
In addition, a Jokos file (number 36367) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.