Something got into man's being. Something got into man's body. So it was not simply a matter of commiting a transgression. It was also a matter of being poisoned with something.
So some folks believe.
Others have more of the following belief:
Sin lies only in hurting other people unnecessarily. All other "sins" are invented nonsense. (Hurting yourself is not sinful -- just stupid).
Robert A. Heinlein, Time Enough for Love, 1973
Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.