It's pretty much a pointless discussion, in my opinion. While you can be tied down by biological, social, and situational pressures, you always have the choice not to follow them. Or even to take a third option. There's no real room for a free will discussion because even if you FEEL trapped, you never truly are.
More philosophically:
You believe life is opened-ended, a series of choices, a naked frolic through the twin fields of possibility and freedom and thus free will exists...
OR
You believe that all choices are pre-determined and the immovable hand of destiny *****-slaps you down a path you have no power to change, so free will doesn't exist.
There's really no middle ground unless you think destiny is some slightly lenient force that only pushes you in a certain direction or calls once in a while to see if you want to hang out.
But then again, the original concept of "destiny" really didn't have any wiggle room. Destiny was unchangeable, so that *****-slap was coming your way whether you liked it or not.
Either way, there's no way to go back to the past, despite what we all wish, and so there is only one path things will ever take. Whether you believe it's just one path of infinite possibilities, or the only path that can happen is just a matter of personal preference.
Then there's that scientific theory that EVERYTHING in the universe, including your own choices as a person, are predetermined on a physics/chemical/biological/atomic/blahblah level down a path that was put in motion at the big bang or whatever.
Personally I think that's a terrifying theory.
The very fact that we're having this discussion at this time could just be the result of SCIENCE, you guys.
Personally, I try not to think about this topic. If you do want to, remember: either side has positives:
(free will: we're free! endless possibilitieeeees)
(destiny: no use worrying about things because it's all meant to be)
negatives:
(free will: Responsibility for all misfortune you encounter/regret)
(destiny: there's no point to all of this/depression.)