Cohen-Blind was born in Mannheim, Grand Duchy of Baden to Jacob Abraham Cohen and his second wife Friederike, née Ettlinger. Shortly after her son's birth, Friederike began a relationship with journalist and revolutionary Karl Blind, a former student of the University of Heidelberg who had been expelled for expressing radical democratic sentiments. She financially supported Blind's political activities and was arrested with him in the summer of 1847. They married after Jacob Cohen's death in 1848, at which time Ferdinand's last name was changed to Cohen-Blind.