Kurt Moser was born on August 1, 1891 in Kolberg/Pomerania as the son of the grain merchant Albert Moses and his wife Julie née Lubszynski under the family name "Moses". He had 5 brothers: Arthur, Georg, Ernst, Fritz and Günther. Kurt Moses studied medicine in Berlin and Greifswald. In World War I he served as a staff physician on the Western Front, and because of multiple war injuries he received the Iron Cross II Class. After the end of the war, he specialized in gynecology and disease control. In 1922 he and his brothers changed the family name to "Moser".

Günther Moser was born on June 13, 1899 in Kolberg/Pomerania as the son of the grain merchant Albert Moses and his wife Julie née Lubszynski under the family name "Moses". He had 5 brothers: Arthur, Georg, Ernst, Fritz and Kurt. Like his brothers, he attended the Kolberg Cathedral and Realgymnasium and did not receive a Jewish education because his father was estranged from the rabbi. He served in World War I from 1917 to 1918 on the Western Front and suffered an injury to the cornea, which later also led to almost total blindness due to inadequate treatment.

Erna Ella Rahel Moser was born in Berlin on June 21, 1906, the daughter of the merchant Max Moser and his wife Hulda, née Friedländer.

Erna Weitzmann was born in Berlin on March 10, 1890 to Jewish parents. Nothing is known about her family, her parents and siblings. She married a man named Mischlewitz and was later divorced. The marriage remained childless. In her declaration of assets, Erna Mischlewitz stated that she was a corset seamstress by profession. She did not declare a single item as property; she was a lodger with Julius Moses without any furniture or furnishings of her own.