You're right - I don't get that being a product of my genes and environment deprives me of a significant degree of free will in choosing courses of action. I believe the combination of these two factors actually enhances my ability to evaluate and choose between different destinies of broadly equivalent validity.
The choices you make are a result of those factors, though. There may be multiple choices in front of you at any given time, but your genes and environment determine which of those choices you will ultimately make. There is even evidence that choices are made before we are even consciously aware of having made them.
Do you understand what I'm saying yet?