We don't have free-will. Sorry. And this is why

Regarding free-will we have to look at the decision-making process – Does the brain exhibit any proof of self-control? We have certain mechanisms of self-control to the extent of deciding the means to a certain end. That is the farthest free-will can go – that is its maximum extension. The limit lies on deciding what is the end. Because free-will is creating the decision, with no causal background, and such thing does not exist, at least among us.

And we know that to be true because we can trace a nexus of causality back through the known time and space which results in a predetermination of the beginning of mankind, its existence and end. And now that you heard this, there is no way to get out. Everything you decide to do, you must understand that such was already predetermined.

If this idea makes your life bleak, unforgiving and ultimately futile, i am sorry to be the bearer of bad news

Each person lives in a gargantuan system of influences. No person made himself and didn’t determine anything about themselves that they would use as an example of their exercise of their freewill. Nothing about you was created by yourself. All your dispositions and efforts are nothing that you have particularly authored.

This is LaPlace's Determinism, aka LaPlace's Demon.

If someone (the Demon) knows the precise location and momentum of every atom in the universe, their past and future values for any given time are entailed; they can be calculated. (The reason we use the expression Demon, is because back when this was proposed, there was no concept of "supercomputer")

Basically, we may regard the present state of the universe as the effect of its past and the cause of its future. An intellect which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, it would embrace in a single formula the movements of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes.

So, you know why you just scratched your arm? The reason can be traced to the big-bang.

Under the strict demon hypothesis all details are known—to infinite precision—and therefore variations in starting conditions are non-existent. Determinism posits that all activity in the universe is both (i) the effect of [all] prior activity, and (ii) the only activity that can occur given the prior activity. That is what is meant by saying that everything is “determined” — it is the inexorable consequence of activity that preceded it.