Except of course that God chose to make them that way in the first place. Thus, either God changed Its mind after realizing "Hey, waitaminute. They can't reproduce and multiply if they aren't corrupted by sinful thoughts!" OR God always intended to screw them over by putting them in the aforementioned Catch-22.

That poor serpent! He gets such a bad rap! He was basically Morpheus and the apple (or fig. Or date) was totally the original Red Pill.