This is fallacious reasoning, and it can be easily demonstrated to be fallacious reasoning by just reversing the situation. IOW, what would have happened had Adam and his accomplice not eaten the fruit? To be consistent, wouldn't we have to say that this would have made them inherently good? I think so. But yet, to say that we are "inherently" one way or the other flies in the face of free will, for if we were incapable of wrong-doing, we'd be the equivalent of robots programmed to never to do wrong. But of course, Christianity would have us believe that we are "inherently evil", and yet, look, we aren't incapable of doing "good". The inconsistency is glaring. But for the time being, let's move on to the supposed moral "standard"---the standard from which we supposedly fall short.
In a few short steps it can be demonstrated that the biblical standard of morality - that is, the morality that we're to be shooting for - is subjective.
If "wrong"(aka "sin") is defined as going against whatever God says, then right away we see that "wrong" is a relative thing, not an absolute thing. If "God" doesn't get his/her/its sense of "right"/"wrong" from an external source, but instead, IS the source, then whatever this God deems "good" at any given moment is completely arbitrary. This, BTW, is very dangerous. Think about it---if nothing prevents this God from waking up one day and deciding that slavery is "good", then from a theist POV, slavery is "good" if God says so. On the other hand, if there is something preventing this God from deciding that slavery is "good", then right away we see that there are values outside of/independent of this God to which he/she/it adheres. And for the record, I used slavery in my example because the bible condones slavery. If the apologetic(defense) is that this is Old Testament/Old Law, etc., and therefore such things are obsolete, then this is yet more compelling evidence that biblical morality is relative to the time, and in which case, it is not "objective", as the bible and Christians claim it is.