With William Finck and Sven Longshanks
The early Church used to teach that there were two seed-lines, one from Adam and one from Cain.
This can be shown from the writings of Tertullian, Justin Martyr, Ignatius of Antioch and others of the Church Fathers.
As well as this, there are also copious references to it in the Books of Adam and Eve, which were complied by the Eastern Church in the third to sixth centuries.
Clement, Eusebius and Origen obscured this teaching in favour of a universalist position, but it still did not fully take hold until the later Schism and the loss of the Celtic church, who conformed to scripture only, rather than the new Catholic hierarchy.