Martin was married on 26.11.1918 to Anna Sofie Sternfeld-Retzke, born in 1892 in Berlin. She was almost certainly non-Jewish, and she survived the war and was living in 1954 in Berlin-Zehlendorf. (Amsterdam City Archive Card)
There is a tragic irony in the fact that most Jewish families with a "mixed marriage", ie a non-Jewish family member, were largely protected from deportation when they lived in Germany, but lost this protection when living in the occupied countries. If the the Sternfeld family had remained in Berlin, it is most likely that none of them would have been deported.
Addition