Interesting question. The concept of free will pre-supposes I have an independent, thinking consciousness. As Descarte said "I think, therefore I am". But, what exactly is consciousness? Is it merely a function of our brains? According to evolution, consciousness is just a product of higher brain function: at some point during the evolution our brains, consciousness just happened.
If I exclude any supernatural explanation for my existence, and limit myself to a strictly a naturalistic explanation of consciousness, then I don't believe free will exists.
If evolution is true, and consciousness is just brain function, then my thoughts must be completely deterministic; governed by scientific laws. My interest in bees or admiration of a well-executed double-play in baseball is nothing more than a particular combination of neurons firing in my brain. Just as a cloud is a material object governed by things such as air pressure, wind, etcetera, if consciousness is material, then all the things I do are fixed by my environment, my genetics and so forth. There is no free will. None.
As British evolutionist J.B.S. Haldane said: "If my mental processes are determined wholly by the atoms in my brain, I have no reason to suppose my beliefs are true...and hence I have no reason for supposing that my brain is composed of atoms."
Philosopher Michael Ruse put it this way:
"Why should a bunch of atoms have thinking ability? Why should I, even as I write now, be able to reflect on what I am doing and why should you, even as you read now, be able to ponder my points, agreeing or disagreeing, with pleasure or pain, deciding to refute me or deciding that I am just not worth the effort? No one, certainly not the Darwinian as such, seems to have any answer to this...the point is that there is no scientific answer."
My personal belief is in a Creator, who created Man in his image, with a consciousness and free will.