Clara Engel was born on May 10, 1872 in Schwetz/East Prussia, the daughter of Jakob Engel and his wife Rahel née Buchowzer.

Jakob Julius Less was born in Rössel on December 7, 1885, the son of Hirsch Hermann Less, a horse dealer, and his wife Friederike, née Herz. He married Helene Levy in Berlin in 1912,
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