Eugen Dido Kvaternik was the son of Slavko Kvaternik, a general in the Independent State of Croatia army and a member of the Ustaše, and Olga Frank, daughter of Josip Frank, a Catholic convert whose parents were Jewish.

Kvaternik was sentenced to death in absentia by France for organizing the assassination of King Alexander I of Yugoslavia.

He was released in 1936, having served two years, whereupon he joined the exiled Ustasha members on the island of Lipari.

Dido Kvaternik died in a car crash in Río Cuarto, Argentina in 1962.

Slavko later became a professor of political sciences in Argentina, and Davor became a cardiologist in Boston, Massachusetts.