Walter Michel Poppert was a son of Siegmund Poppert and Selma Rauner. He married in Amsterdam on 22 December 1938 to Gertrud Schönborn, daughter of Anton Schönborn en Selma Rosenbaum.
Walter Michel had another brother, a manufacturer of ladies fashion hats in Zaandam: Erich Karl Poppert.
City Archive of Amsterdam, archive card of Walter Michel Poppert and Gertrud Schönborn.