On the one hand, they often seem to have a physical predisposition toward alcohol consumption. There are many other influences as well, such as culture, peer, and habit. So staying away from alcohol becomes a supreme struggle. It is a battle the alcoholic can lose, and which can repeat over and over again. Very possibly, but then you are just subject to a new level of control.
People do things all the time.
Behavior isn't arbitrary - your behavior is still determined by something . If the person wanted to be more macho or feel more in control of himself, he can certainly have that feeling. If he considers some behavior immoral, and wants to feel in control of it, he probably can be after completing Marine boot-camp. But anytime he does something, his behavior can still be traced back to some causal influence. It is at this point that it becomes easy to believe that we are as programmable as computers.