FREE-WILL IS OUR ILLUSION. Why did I do that!? What was I thinking? Behavior is a curious phenomenon and we may often wonder why we do the things we do. In short, it's because of our cells. Our behavior, the decisions we make and the actions we take, are nothing more than cellular responses. How our cells interpret their immediate environment dictates how we respond to our environment. Studies of behavior show that often we are unaware of why we make the decisions we do, and that these decisions can be easily manipulated and influenced by subtle environmental cues. What may seem like a free will decision may indeed not be so. My cells made me do it, explains the phenomenon of behavior as a matter of cellular determinism.