The Greek text (Textus Receptus) of Romans 5:12 reads:
δια τουτο ωσπερ δι ενος ανθρωπου η αμαρτια εις τον κοσμον εισηλθεν και δια της αμαρτιας ο θανατος και ουτως εις παντας ανθρωπους ο θανατος διηλθεν εφ ω παντες ημαρτον
Which one fairly literal translation (The Orthodox New Testament Praxapostolos) renders:
Therefore, even as through one man sin entered into the world, and death through sin, and thus death passed to all men, on account of which all have sinned
But the Vulgate translates the final phrase ("on account of which all have sinned" - εφ ω παντες ημαρτον) as in quo omnes peccaverunt. The Douay-Rheims translation of the Vulgate reads therefore:
Wherefore as by one man sin entered into this world and by sin death: and so death passed upon all men, in whom all have sinned.
The implication is that somehow all have sinned in Adam - i.e. they inherit the guilt of Adam's sin. Unless I am misunderstanding the apparatus, there is no variant in the Greek text that supports this wording. John Chrysostom - a 4th century Greek Doctor of the Roman Catholic Church - does not seem to interpret the verse this way in his homily on the passage.
My understanding is that the verse appeared this way in Latin in Augustine's De Peccato Originale, which also introduced the term "original sin" in the west, though perhaps that was not the first occurrence.
It seems that the Augustinian-Vulgate understanding of this verse has seeped into other English translations to various degrees. While the King James is close to the literal translation above (And so death passed upon all men, for that all have sinned), other translations follow more closely the Latin meaning. The ESV and RSV state, for example, ... and so death spread to all men because all sinned (i.e. cause and effect are transposed).
Is there some reasoned explanation for the apparent departure of the Vulgate from the Greek text of Romans 5:12?
(Perhaps this should be posted in BH instead, but since the passage of interest touches on theological differences between Christians I thought to post it here.)