Isaac Betel was a son of Simon Betel and Elisabeth Polak. He married 19 April 1906 in Amsterdam to Betje Piller, a daughter of Leendert Piller and Anna Mossel. Besides the at home living son Nathan, there were two other sons who lived elsewhere: Leonard and Simon.
City Archive of Amsterdam, archive card of Isaac Betel, Simon Betel and website www.wiewaswie.nl.