If you look hard enough (and I sure had to look hard for this one) can`t you find suggestions within the Bible of instinctual knowledge of what is right and wrong?
as in:
1 John 2:27 But the anointing which ye have received of him abideth in you, and ye need not that any man teach you: but as the same anointing teacheth you of all things, and is truth, and is no lie, and even as it hath taught you, ye shall abide in him.
I recall passages relating to explanations of the Holy Ghost as suggesting divine knowledge is emitted from It/God.
But this theology would conflict with your opinion that we got our moral code from the Bible because it suggests instinctual knowledge of right and wrong.