Gertrud Käthe Chodziesner was born in Berlin on December 10, 1894 into an assimilated German-Jewish family. Her father Ludwig Chodziesner, a loyal monarchist, worked as a criminal lawyer. Her mother Elise (Schönflies) Chodziesner came from an intellectual mercantile family. Kolmar would later take her pseudonym from the German name of the town Chodziez in the province of Posen (Poznan), where her father’s family originated.
Kolmar grew up in a family that loved to read and write, perform plays and read prose at the dinner table. Although her father had published short stories in the local paper Kolmar was apprehensive about making her own writing public. She had no ties to the literary community of Berlin even though she had written fictional works since her childhood and her family welcomed such interactions.