Johan Marie Koornwinder (Joop) grew up in modest circumstances. Together with his brother Wim he worked for a mattress company in Utrecht called DWU, "De Wijze Uil", owned by David Wijzenbeek. Mr. Wijzenbeek was a Jew married to a non-Jewish wife. During the war between 1940-1945 the Wijzenbeek family had to go into hiding. Joop worked at DWU during these turbulent years as did his soon-to-be wife Antje Cornelia Schreuder (Ans) and her sister, Rie, who also met her husband at DWU, Wout Heyveld.

After the war, Joop left DWU. The rest of Joop's career is not known at this time, but we do know that he rejoined his brother at Olga, another mattress factory based in Leiden, in the later years of his life and helped Olga attain its national success.

Joop was a dedicated family man and loved his children and grandchildren enormously.