>your decision process was programmed into your brain by nature & nurture,
But that's asserting the absence of free will, which you can't do in an argument meant to prove the absence of free will. Your interpretation of a free will experiment can't involve assuming a-priori that there is no free will.
Any discussion about free will should probably start with an agreed-upon definition of what "free will" is and what might be needed to confirm that it does or doesn't exist.
