Evolution of Doctrine: Original Sin
In the history of Christian theology there have been a number of major theological changes made in Western Christian theology over the course of time, often due to the use of inaccurate Latin bible translations.
The earliest of these changes chronologically was the doctrine of Original Sin. The Christian church in the second century AD had nothing remotely resembling the doctrine of original sin as we know it today. The universal view attested is that children are born innocent and that people are guilty only of their own sins. In some writers the concept that Adam's sin damaged the likeness of God within humanity somewhat, and this is viewed as a kind of corruption of the natural order which is inherited - and this is generally taken to explain why humans die. But this is not taken to imply any inevitability to human sinfulness or any damage to free will. There is a dominating belief that through human effort and the assistance of the Holy Spirit and Christ's example, humans can live godly lives that are upright and pleasing to God.
In the late second century, in North Africa, the writer Tertullian protested against the introduction of the practice of infant baptism there. He argued that baptism was supposed to be for the forgiveness of sins, but since infants had no sin the introduction of its use for them was wrong. The widespread thought however seemed to be that there might be some mysterious gracious blessing from God conveyed through baptism, and thus infant baptism quickly became a fairly universal custom.
In third and fourth century North African Latin Christianity, there is a clear trend present towards taking a darker view of the human condition. In the course of these centuries the theologians in this area began to take the view that humanity had been very seriously damaged by the fall, that humanity was bad, that the human will is not capable of becoming good, and that all humans are born guilty of Adam's sin. It appears that a couple of generations after Tertullian, people had started using his same logic backwards: "We baptise infants, baptism is for forgiveness of sin, therefore infants must have sin." Such doctrinal changes were geographically fairly confined. Greek Christian writings from during and after this period reflect an unchanged stance on the subject - eg John Chrysostom (d. 407), states explicitly that infants have no sin and that forgiveness of sin is not the motive for infant baptism.
Nor, it seems, had these innovations reached too far to the west. When a monk from England named Pelagius journeyed to Rome he was shocked by the theology he encountered there. He felt that the teachings of the North African bishop Augustine effectively denied the possibility of good moral conduct and human moral reform which Pelagius (in line with typical Christianity of earlier centuries) saw as the foundations of Christianity. Augustine had gone further than his North African predecessors and actually advocated Predestination, a doctrine that had always previously been strongly opposed by Christians. This led to an extended controversy between Pelagius and Augustine. Scholars are generally agreed that Pelagius' viewpoints by and large were typical of previous Christian orthodoxy (especially the Greek-speaking church at the time, who couldn't read Augustine's writings) and Augustine's were radically new. Nonetheless Augustine managed to use his influence to get Pelagius condemned as a heretic: "it was an injustice that made history" writes the renowned Lutheran patristics scholar Jaroslav Pelikan in his The Emergence of the Catholic Tradition (pg 313).
One passage that Augustine drew heavily on in his arguments with Pelagius was Romans 5:12, which in the Latin translation (he couldn't read Greek) said that everyone had sinned "in" Adam. Augustine used this to argue that all humanity was present "in" Adam when he sinned, and thus all are born guilty of sin. His Latin translation was extremely faulty here however, and it actually reads in the Greek that everyone dies "because" they sin or that everyone dies "because of which" they sin.
Thus the doctrine of Original Sin became standard within Latin Christianity. The Greek Christians however (who were at that time a large majority of Christendom), never read Augustine's writings and continued to hold their traditional doctrines. To this day the Eastern Orthodox Christians continue to totally reject the Latin innovations of the doctrine of Original Sin. Unsurprisingly when we turn from history to the Bible, there isn't much in the bible that could lend itself in support to the Latin doctrine of Original Sin. Nor did the Jewish Rabbis teach such a doctrine, and Judaism today rejects any such doctrine.
And that's how the standard Protestant doctrine of Original Sin resulted from the introduction of infant baptism, a bad Latin translation, a conflict where influence beat orthodoxy, and a couple of centuries of doctrinal change.