In this blog post, we will look at which has a greater influence on the formation of a person’s personality and behavior: genetic or environmental factors.
The question of how humans were created has been around for a long time. With the advancement of science and technology, this question is gradually being answered. Starting with the discovery of the DNA double helix structure by Watson and Crick, the DNA base sequence is gradually being elucidated, and research on genes is also being actively conducted. In the early days, genes were thought to determine only physical characteristics, but as time went on, the view that genes also play a role in the formation of human personality began to emerge. The conflict between scientists over the formation of human personality became more intense when Francis Galton first used the words “nature and nurture.”
Those who believe that nature is more important in the formation of human personality argue that innate genes cannot be changed. They believe that genes control not only human physical characteristics but also emotions and behaviors. They have developed a theory called genetic determinism. Genetic determinism is the view that the behavior of an organism is determined by the combination of genes, and it claims that human social behavior is also influenced by genes. According to this theory, genetic research can predict what behavior an organism will have, what diseases it will suffer from, and what appearance it will have. As DNA research progressed, more and more people supported genetic determinism, thinking that they could unlock the secrets of human formation by revealing the secrets of genes. Supporters of genetic determinism started the Human Genome Project accordingly. The Human Genome Project is a project to find and list all genes in the human body, and supporters of genetic determinism tried to prove that numerous genes regulate human formation through this project. This way of thinking originated from reductionism, which is the belief that the causes of complex phenomena can be reduced to simpler phenomena for analysis. Modern biology developed based on this reductionism. As science progressed, scientists tended to analyze things in smaller and smaller units, which led to the discovery of cells and DNA. This approach was excellent as a research method, but not as a method of interpretation. According to the reductionist approach, gene expression is a one-way process that forms from small units to large units. This is called the “central dogma,” and it claims that DNA is the primary cause of determining the properties of proteins in the one-way information transfer from DNA to proteins.
However, the results of the Human Genome Project showed a different direction than expected. According to genetic determinism, there are numerous proteins in humans, and if we consider the genes that regulate the activity of the genes that encode these proteins, there should be at least 120,000 genes in human chromosomes. However, the results of the study revealed that there are only 25,000 genes in humans. This means that genes do not control everything in humans. Even in the primitive life form of the nematode worm, there are 24,000 genes, and in the fruit fly, there are about 15,000 genes. This suggests that one trait does not correspond to one gene, meaning that genes do not determine everything about humans. Therefore, it can be concluded that other factors, not just genes, play a more important role in the formation of humans.
Contrary to genetic determinism, a new theory called epigenetics has emerged. When the Human Genome Project, which began with a reductionist approach, failed to prove genetic determinism, scientists tried a new direction of research. As a result, it was found that environmental influences can alter DNA, or genes. It is not that trait formation begins unilaterally in DNA, but that it is regulated by environmental signals. The activity of genes is regulated by regulatory proteins, and environmental signals control these regulatory proteins. Research results that environmental signals have generated more than 2,000 protein variants from the same gene through regulatory proteins also support the involvement of environmental influences in human formation. Genes do not directly control their own activities. Gene expression is achieved through the action of effector proteins, which are regulated by environmental signals captured by cell membrane receptors. In other words, the expression of a gene is regulated by environmental factors, not the gene itself. An experiment conducted on mice with the agouti gene supports this claim. Mice with the agouti gene are characterized by yellow fur and obesity. When mice carrying this gene were fed food that blocked gene activity, the mother mice carrying this gene gave birth to offspring with brown fur and slender bodies. This shows that the environmental changes experienced by the mother mice also affected their offspring. Gene expression was regulated by the environmental factor of food. This means that genetic determinism is wrong.
The fact that genetic determinism is wrong can also be seen in historical events. During the Nazi regime, the Holocaust was based on eugenics, which was based on genetic determinism. Eugenics is a discipline that studies artificial selection to preserve superior genes, based on the premise that there is a superiority between genes. Those who believed that genes determine everything in the past also thought that human talents and characteristics are inherited. This eventually led to the classification of people with superior genes and those with inferior genes. In the 19th century, this eugenics spread to various countries and developed into the classification of racial superiority. Differences in genes by race led to the distinction between superior and inferior races. Eventually, the Holocaust, or the Jewish genocide, occurred in Germany due to the influence of this eugenics. After these events, eugenics began to decline as its fallacy was revealed. This proved that there is no superiority or inferiority between genes, and that human differences are not related to genetic differences. In other words, the role of nature (genes) in human formation is not significant.
Now, let’s look at the aspect of parenting. The view that parenting is more important than nature is based on environmental determinism. Environmental determinism claims that the environment plays a more important role in human formation than genes. According to this theory, living things are not beings governed by genes, but beings that actively change according to the environment. This means that the flow of information is not one-way, but is made up of interactions like a net. In other words, it means that the factors involved in human formation are related to each other and interact with each other. Recent studies have shown that proteins in cells interact with the influence of the external environment. Environmental determinists support epigenetics, emphasizing that human formation is determined by the environment. Epigenetics claims that environmental factors regulate gene expression, which is manifested as changes in gene expression rather than changes in genes. Environmental determinism also emphasizes plasticism, that is, the ability of organisms to adapt to the environment.
Genes are important factors that determine human physical characteristics and behavior. However, genes are not fixed, but have the potential to change according to environmental signals. This suggests that genetic determinism is wrong. Genetic determinism, which is based on the assumption that genes do not change, is no longer supported by the emergence of epigenetics, which shows that gene expression can change due to environmental influences. The fact that gene expression can be regulated by environmental factors emphasizes the fact that environment (upbringing) is more important than nature (genes) in human formation. Human formation is achieved through the interaction of nature and upbringing. Genes provide the basic framework for human formation, but environmental factors serve to shape and express that framework. In human formation, genes and the environment influence and shape each other.
Identical twins are a good example of this interaction. Identical twins have the same genes and look alike. However, if they grow up in different environments, they can have completely different personalities. This shows that even if genes are the same, environmental factors can affect how a person develops. Another example is Tiger Woods. He is considered one of the greatest golfers in history. Tiger Woods’s ability to become the best golfer is not only due to his natural physical talent, but also to the environment in which he grew up. His father taught him golf from a young age and put a lot of effort into developing his talent. These environmental factors allowed Tiger Woods to become the best player. In other words, environmental factors played a more important role in his success than his natural talent.
In conclusion, it is difficult to conclude which is more important in human development: nature or nurture. It is true that genes and the environment interact to shape humans. Recent studies suggest that environmental factors play a more important role. Genes provide the basic framework for human formation, but it is environmental factors that fill and embody that framework. Therefore, the most important factor in human formation is not genes but the surrounding environment in which the person has lived.
