Marchionne was born in Chieti, Abruzzo, Italy, the son of Concezio Marchionne, from Cugnoli (Abruzzo), and Maria Zuccon from Carnizza (today Krnica, Croatia) near Pula in Istria. His father served as a "Carabiniere" in Istria, where he met his future wife. Marchionne's grandfather, Giacomo Zuccon, was killed in September 1943 by Yugoslav Partisans near Barban in Istria, while his uncle Giuseppe Zuccon was killed by the Nazis the same year. In 1945, when the region was occupied by the Yugoslav army, Marchionne's parents moved to Chieti in Abruzzo, where Sergio was born.