Born in Wegeleben (now in Saxony-Anhalt) in the Kingdom of Prussia in the German Empire, Bormann was the son of Theodor Bormann (1862–1903), a post office employee, and his second wife, Antonie Bernhardine Mennong. The family was Lutheran. He had two half-siblings (Else and Walter Bormann) from his father's earlier marriage to Louise Grobler, who died in 1898. Antonie Bormann gave birth to three sons, one of whom died in infancy. Martin and Albert (1902–89) survived to adulthood. Theodor died when Bormann was three, and his mother soon remarried.