Petraeus was born in Cornwall-on-Hudson, New York, the son of Miriam (née Howell), a librarian, and Sixtus Petraeus, a sea captain from Franeker, Netherlands.His mother was American and his father had immigrated to the United States from the Netherlands during the initial phase of World War II. Sixtus settled in Cornwall-on-Hudson, where David Petraeus grew up and graduated from Cornwall Central High School in 1970.
Who was Sixtus? Glad you asked:
There were two popes with the name of Xystus in the early Church, though that mentioned in the Canon of the Mass, various commentaries suggest, was St. Sixtus II who reigned as pope only from A.D. 257-258, at which time he was martyred under the persecutions of the Emperor Valerian. A letter of St. Cyprian suggest he was captured in the catacomb of Callistus and immediately executed, though the method of his execution is debated.
FWIW, Petraeus’s official biography notes that he studied at Georgetown on a military fellowship from 1994-95. All of which makes me wonder if the general is, perhaps, Catholic. (His biography is silent on this point.)