Biology is chemistry, chemistry is physics, physics is deterministic. Therefore, by the transitive property, biology is deterministic. Everything that happens inside your body, from neural signals to metabolizing cells are just chemical reactions, which again, abides by the law of physics. In the NPR segment, Hardwire, it states that, “...no agency at all...I don’t think there is a shred of free will out there.... Free-will is the biology that has not been discovered yet.” This free will vs. determinism argument, to a large extent, parallels science and religion. People explain the unknown with religion, until science finds an answer. Likewise, people tend to explain their uniqueness with free-will until science finds an answer. For example, most people would think Judges would possess free-will in order to give the fairest sentence to each unique case. However, in Israel, judges in parole hearings had their sentences most highly correlated to the time they last had a meal. People’s lives were determined by the chemical signals one’s lunch released into one’s brain.
Furthermore, the technology exists today to reprogram our biology to determine many aspects of our future offspring. Experts agree that more than basic traits like hair color, height, or weight can be predetermined through gene-editing. More complex human traits like personality and behavior may be able to be engineered. In fact, the “mice licking experiment” corroborates this deterministic trait of biology. Even though mice were licked by their non-biological parents, these mice exerted similar behaviors to their offspring. This was described as a “cascade of biological events that the care of the mother triggers chemical signals that goes to the nucleus...” In essence, this past experience changed the biology of the mice, which, in turn, determined its future behavior.
In short, decisions are made on personality (largely comprised of genetics) and experiences (based on your personality and the past, which you can’t control). These two components are very interconnected. Studies show that experiences can result in long term changes due to genes being reprogrammed. For example, during an ice storm in Quebec, pregnant mothers had a greater rate of offspring with disorders like autism and autoimmune disease.