We have genuine free will. We really can choose or choose otherwise. I believe that the only reason this is true is because God insisted on it when He made us. Our reality would be deterministic if not for God's gift of freedom. God is love and love is only possible in the context of relationships. He made us to share love and fellowship with us. He wants us to freely return those things to Him. This necessitates freewill.
The brain is an electrical/chemical machine. As such, it controls what the body does on a continual basis. The complexity at which the brain operates make it impossible for an individual to follow it's computations in real-time. This would seem to indicate that the brain is always making decisions on a subconscious level and then relaying these decisions to the conscious level. We know that the brain makes simple life sustaining decisions on a subconscious level such as breathing. Why would complex decisions need to be controlled any differently?
The five senses are the only means by which information is delivered to the brain. The brain is building its' own algorithms to make decisions based on that information. The genetic code, the trillions of connections will be used to make future decisions based on real-time sensory information. How these electrical/chemical algorithms are weighted depends on the perceived importance of the experiences of the individual as his brain learns.
Experiences come from many different sources, Mother, father, sister(s), brother(s), all the other relatives, friends of the parents, friends of the siblings, personal friends, teachers, classmates, incidental people met through the course of the day, pets, books, television, computer, radio, toys, every other physical item encountered (hot stove, water, etc.) and of course, alone time.
The prefrontal cortex is responsible for regulating behavior. The brain tries to figure out what the person needs to survive in their environment. The main functions of the prefrontal cortex involve planning responses to complex and difficult problems. The prefrontal cortex takes past events stored in those billions of neurons and present experiences, runs them through brain created algorithms, and sends a response to the body.
The brain spends its' first ten years learning, by creating synapses for everything in the individuals life. Then in the next ten to fifteen
years, the brain takes those synapses and fine-tunes behavior, emotions and planning. All the while the brain recalculates algorithms to create what it thinks is the best responses for any situation that it may encounter. What is finally created is an electrical/chemical computer that runs the body both unconsciously and consciously. The individual reacts to real-time situations based on the response from the brain after the real-time input is processed through previously created algorithms. The individual does not make a decision randomly which is what the incorrect definition of free will
Based on all of this information, every living human beings' decision making is based on past information that has been assimilated by the brain. The responses come from the brain based on the perceived situation. The physical body just completes the response as ordered. There never is an either/or choice by the physical body in real-time. The brain has already made the choice and passed it on to the body. Even past tense thinking about “I could have done that instead” is nothing more that the brain double checking its' own algorithms for possible improvement in a future decision making situation.