St Augustine of Hippo had a profound effect on the Catholic Church that many people don’t appreciate.
In these Confessions, Augustine argues that it was human choice – Adam’s sin or original sin – that brought mortality and sexual desire upon the human race and so deprived Adam’s progeny of the freedom to choose not to sin.
When Augustine was a younger man and had a mistress, he wrote a book On Free Will which agreed with the views of Pelagius, but he changed his mind later in life as indicated in these Confessions.
In this book, he argues that human beings are not free, as Adam was, to resist sin. Humans have no power to choose not to sin and we can’t even control our sexual impulses.
In this book, Augustine refers to his past dalliances with women, his involvement with the Manichaean version of Christian doctrine, and his subsequent conversion to the way of Christ.
Ever since Augustine, the hereditary transmission of original sin has been the official doctrine of the Catholic Church.