to the Godfather himself, Don Vito Corleone, born December 7 as revealed in the flashback sequence at the end of Godfather II.
Also, Sonny’s reaction when Michael mentions the number of men who enlisted in the army after Pearl Harbor proves the Corleones are true paleos:

Sonny: Bunch of saps, they give their lives for strangers.

Michael: For their country.

Sonny: Your country’s not your blood.