Fritz Rosenberg was born in Berlin on July 6, 1901, the son of Leopold Rosenberg, a self-employed upholsterer, and his wife Eva, née Engel.

Born December 2, 1898 in Berlin

Eva Engel was born on September 16, 1870 in Schwetz/East Prussia, the daughter of Jakob Engel and his wife Rahel née Buchowzer.

Otto Rosanes was born on August 8, 1877 in Breslau into a Jewish family.

Betty Lazarus was born in Berlin on February 15, 1874 to Jewish parents Ida Lazarus and her husband. Nothing is known about her youth. On September 16, 1894, she married Daniel Ries. Together with Emil Steffen, he had been running a metal trade since 1903, first in Alt Moabit, later at Flottenstrasse 54/55 in Berlin-Reinickendorf. The marriage produced three children: Käthe, born in Scharmbeck on June 13, 1895, Adelheid (Ada), born in Scharmbeck on February 19, 1897, and Fritz Ries, born in Berlin on December 21, 1903. The family lived in Berlin-Tiergarten, Bochumer Straße 5 I.