Genetic Essentialism: An excuse for just about everything
Our present society has grown accustom to “blaming the genome” as an explanation for certain behaviors or actions. Sex scandals, divorces, addictions, and even the attention span of an elementary-aged child are blamed on the human genome in many of the popular forms of American media. Do these statements have any scientific backing? If so, the human genome could be an excellent excuse for almost anything that may occur in our lifetime. No longer will students come to school and tell their teachers that their dog ate their homework; instead, their genome prevented them from completing it. Considering phenotype as solely dependent upon genotype is an easy assumption to make, but it is important to understand all that contributes to the complexity of the human essence. The doctrine that equates having a human genome with being a human person is referred to as genetic essentialism, and genetic determinism is a similar view that our genes determine our complete phenotype irrespective of the environment. Though genes play a critical role in human development, it is not fair to consider the human genome as the only factor that defines our phenotype. One does not have to venture into a genetics laboratory to understand this concept; it can be seen by comparing a child to its biological parents or any biological sibling it may have. The resemblance offers simple, yet important evidence: the child is not a walking replica of the parents or siblings, but it does share some of the same phenotypical features. “Identical” twins offer another source of evidence that may support the complex nature of the human essence and the role genes do or do not play in the equation. Identical twins have exactly the same genes but are not necessarily the same exact people. One may enjoy sports and the other may be deeply fascinated with developmental biology. If genetic determinism is correct, how can it explain these phenomena? The differences in the gene expression of each individual is not only derived from the shuffling of genes that occurs during meiosis of the parents gametes, but also from many environmental factors; this is referred to as developmental plasticity. Developmental biologists who seek to better understand the human essence have carefully studied the role of the environment in the development of an organism. Environmental sex determination is seen in many species such as Thalassoma bifasciatum and everybody’s favorite fish, Amphiprion (Nemo). Wing coloration in certain butterflies is also regulated by certain environmental factors. In humans, the gulonolactone oxidase enzyme (needed to synthesize vitamin C) is absent, which means we must obtain vitamin C through our nutrition. This study alone should be enough to effectively influence any individual who refuses to appreciate the role the environment plays in human development. Intestinal development relies on bacterial symbiosis to form the gut-associated lymphoid tissue (GALT), essential in preventing the body from mounting an immune response to the ingested food that enters the gastrointestinal tract. Another piece of evidence providing support against genetic determinism is the role of differential DNA methylation in human gene expression. This methylation can be affected by the environment, which leads to a modified genome and thus a different phenotype. As humans, our capacity to learn is extraordinary, and some studies have shown that it may even begin while we are still in the womb. Given the evidence supporting developmental plasticity, it seems almost absurd to consider genetic determinism at all reasonable. In my opinion, genetic determinism negates the very nature of a human being by reducing it to a mathematical equation that, unfortunately, is constantly being taken advantage of in American popular media.
