Marcus Kopuit was a son of Louis Kopuit and Jansje Matteman. He was previoulsy married to Sara Trompetter in 1905 in Zaandam. She passed away in 1934. They had four children, among whom Louis Alexander (who passed away in 1908) and Jeannette. Two children survived the war.
Stadsarchief Amsterdam, archiefkaart Marcus Kopuit