But humans don't exist in a vacuum, your decision process was programmed into your brain by nature & nurture, and you had no control over either - the decision process for any control you think you might have had was previously programmed into you brain without your choice.
>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.
