In 1921 Fritz Pfeffer married Vera Bythiner (31 March 1904 – 30 September 1942), who was born in Posen in Imperial Germany (now Poznañ, Poland). The marriage produced a son, Werner Peter Pfeffer (3 April 1927 – 14 February 1995), then the couple divorced in 1932. Fritz was granted custody of the boy and raised him alone until November 1938, when the rising tide of Nazi activity in Germany persuaded him to send him into the care of his brother Ernst in England. Werner emigrated to California in 1945 after his uncle's death and changed his name to Peter Pepper, later establishing a successful office supplies company under that name.