Is Biology Deterministic, Or Do We Actually Have Free Will?
How genes, brains, and environments influence our choices and sense of agency.
Graphic by Dilan Setiya
Imagine taking a genetic test and finding out that you have a high risk for depression. Or absentmindedly reaching out to pick up your coffee and realising that your movement was not driven by conscious thought but solely by neural activity. Modern biology has increasingly suggested that our genes dictate who we are. If this is what truly shapes our impulses and predispositions, then how much of our personality is truly chosen?
A study by Chorney et al. published in Psychological Science, a peer-reviewed journal, reported a statistically significant association between the IGF2R gene on chromosome six and IQ tests, suggesting that intelligence could be biologically determined. Another study by Howard Edenberg published in PubMed Central (an NIH archive) showed that the alcohol dehydrogenase or aldehyde dehydrogenase allele carried by a person influences their level of alcohol consumption and risk of alcoholism. Since drinking behaviours can shape social interactions and self-perception, such biological differences could contribute to one’s personality, how they act and how they perceive themselves. At first glance, these examples seem to suggest that our traits are written into our genome.
However, genetic associations do not imply inevitability. Identical twins separated at birth have different traits and characteristics. In this scenario, Nurture often prevails against Nature. Furthermore, the same mutation in the CFTR gene that causes cystic fibrosis results in different levels of severity for each individual. Genetic background, environmental history, and stochasticity have been found to influence this.
However, in reality our DNA doesn’t work as a rigid footprint. Epigenetics is a process by which environmental factors can directly influence how our genes turn on or off. It works by modifying gene expression without altering our genetic code itself. Through mechanisms like DNA methylation, histone modification, and microRNA activity can switch genes on or off and prevent them from producing proteins, ultimately shaping how traits are expressed. Environmental stimuli such as chronic stress, nutrition, exposure to toxins and other lifestyle factors activate cell signalling pathways that modify gene expression. These are just some of the processes through which our behavior can be altered by our environment. Research by Vogt et al. published in the Journal of Experimental Biology, a peer-reviewed journal, showed that genetically identical shrimp raised in identical environments showed differences in traits due to DNA methylation. This shows that biology alone cannot dictate our identity. It only provides a framework, but environmental exposures and lived experiences shapes how that framework is expressed.
Considering the neuroscientific aspect introduces another layer of complexity. A widely cited study by Libet et al. published on Brain, a highly respected journal, and indexed on PubMed demonstrated that measurable brain activity was detected several hundred milliseconds before individuals had the conscious intention to move. This was first interpreted as the brain “deciding” before conscious awareness. However, it is more accurate to consider that early neural signals reflect a gradual buildup of potential actions and not a finalised decision. Furthermore, higher-order brain regions could override these impulses at any time. So it is safe to say that picking up your coffee without conscious deliberation may not signal a lack of agency, but rather that decision-making has many levels of processing.
Thus, biology does not eliminate free will but establishes inherited predispositions and physiological limits that influence how we think, feel, and respond to the world. Within genetic constraints, there is room for choice. Our behavior is a result of numerous interacting systems amalgamating into one. Genes, environment, and experience continuously interact to produce outcomes that are structured but not totally fixed. It is important to consider that if our impulses arise from biology, they also arise from a biology that has been shaped by a lifetime of experiences with the world. Agency, then, exists not outside biology, but within the complexity of it.
These articles are not intended to serve as medical advice. If you have specific medical concerns, please reach out to your provider.