Know that when Adam and Eve left Paradise they were virgins (‘Ιστεον οτι εξελθοντες ο τε Αδαμ και η Ευα εκ παραδεισου παρθενοι ετυγχανον). In the thirtieth year after their
departure from Paradise <Adam knew his wife Eve and she conceived and> bore
Cain their firstborn and his sister Calmana. And after another thirty years she
gave birth to Abel along with his sister Deborah. (Apocalypse
Pseudo-Methodius: An Alexandrian World Chronicle [trans. Benjamin Garstad;
Dumbarton Oaks Medieval Library 14; Cambridge, Mass.: Harvard University Press,
2012], 3)