It would just be a matter of genetic decay in a fallen world, caused by man's sin. (The fallen world caused by man's sin).
This is absolute nonsense without any scientific validity.
It is certainly nothing to base a theory on.
But, as long as we're dispensing opinions, it is my opinion that the concept of "original sin" is the most evil idea ever to emerge from the fevered brains of shamans. It's not just self-loathing, but self-loathing as a species! That's pure and unadulterated evil.
Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.