I took quantum mechanics in college, and it was a waste of time, for me. Of course, part of that has to do with the fact I got a B- in the course. Anyways, the size and shape of atoms and molecules determine the way they behave, so wouldn't that seem to imply that it would allow for free will?
Further, 99% of the human body is made up of atoms and molecules, if my memory serves me correct. The other 1% is made up of trace elements. Is it possible that those virtually undetectable trace elements give us the free will we use on a daily basis?
Granted, my philosophy skills are rusty, but I wanted to provide a better answer then "Because God made us with the capacity for free will". I hope you enjoyed the holidays, even though I know you're not the biggest fan of Christmas.
But those interactions are triggered by the size, shape, and movement of those molecules, which is different in each person. Couldn't these differences explain, in a very rudimentary way, how free will is triggered?