The earliest Church Fathers do not speak very definitely on the origin of sin, though the idea that it originated in the voluntary transgression and fall of Adam in paradise is already found in the writings of Irenæus. This soon became the prevailing view in the Church, especially in opposition to Gnosticism, which regarded evil as inherent in matter, and as such the product of the Demiurge.
ref.ly/o/stberkhof/636773?length=429
In general the Greek Church Fathers of the third and fourth centuries showed an inclination to discount the connection between the sin of Adam and those of his descendants, while the Latin Church Fathers taught with ever-increasing clearness that the present sinful condition of man finds its explanation in the first transgression of Adam in paradise. The teachings of the Eastern Church finally culminated in Pelagianism, which denied that there was any vital connection between the two, while those of the Western Church reached their culmination in Augustinianism which stressed the fact that we are both guilty and polluted in Adam.
Original sin, as a doctrinal formula, is common to the orthodox creeds for the expression and characterization of native sinfulness. Augustine first brought it into prominence for this purpose, but it is older than Augustine, and its first doctrinal use is ascribed to Tertullian.
http://bible.faithlife.com/books/jmileysysth01/offset/1135214?length=284
