Here’s a great list of quotes about free will via Bill Schloendorn.

While they are all great, this one is my favourite:

Charles Darwin: “…one doubts existence of free will [because] every action determined by heredity, constitution, example of others or teaching of others.” “This view should teach one profound humility, one deserves no credit for anything…nor ought one to blame others.” From Darwin’s notebooks, quoted in Robert Wright, The Moral Animal, pp. 349-50.