Jacob de Jong was a son of Michel de Jong and Naatje Polak. He previously married Roosje Roodenburg in 1910 in Rotterdam. She died in 1935. Together they had nine children of whom one survived the war. Children not living with their parents anymore were Hartog, Michel, Susanna, Isaac, Sophie, Sientj…
In addition, a Jokos file (number 9068) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.