In 1922 Izack Jonathan van Berg married Johanna van Gelder from Groningen. They had a daughter, Frederika. The marriage did not last. Following the divorce, Johanna moved to Groningen with her daughter, where she died in 1934. Until the war years, Izack Jonathan van Berg boarded with a member of the NSB who ran a cafe on the Havenstraat in Winsum. When this arrangement was discontinued, he moved i…