In this blog post, we will examine the influence of genetics and environment on the formation of human character and personality from various perspectives.
The question of “nature versus nurture” has been a controversial topic since it was first raised by anthropologist Francis Galton. Nature refers to innate tendencies such as genes, while nurture refers to all acquired influences beyond the influence of parents. The debate between nativists, who believe that human behavior is related to genes, and empiricists, who argue that experience and environment are more important, is still ongoing. However, it is difficult to say that either side is completely wrong. This is because the question itself cannot be answered by choosing only one side. Both sides have valid points, and extreme conclusions are dangerous. If everything is innate due to genes, then ethics and moral education become meaningless, and if everything is caused by the environment and experience, then it can be said that it is possible to completely transform humans regardless of their innate intelligence or physical condition. Furthermore, if the purpose of this debate is to compare the contributions of each factor, such a question is meaningless and futile because it is impossible to separate the two factors completely. Therefore, rather than viewing nature and nurture as opposing concepts, we should view them as complementary concepts that influence each other in the formation of personality and contribute to the diversity of humanity. The claim that humans are born as a blank slate or that everything is predetermined is overly extreme, and in fact, genes and the environment influence different aspects of development, showing that the role of genes and the environment are not mutually exclusive.
As we can see from history, both extreme nativism and empiricism have ultimately failed. First, there is nativism, or “genetic determinism,” which advocates innate factors. An extreme application of this concept led to the eugenics of Nazism. This was based on social Darwinism, or the idea of “natural selection,” in which inferior genes are eliminated. Hitler believed that Jews and Gypsies had inferior genes and carried out indiscriminate massacres in the name of “natural selection.” Under the concept of eugenics, which aimed to prevent the increase of populations with inferior genes, a horrific genocide was carried out. In contrast to Hitler, the extreme opposite of the acquired nature theory can be found in communism. This theory originated from the idea that people’s innate selfishness can be improved through acquired nature. However, communism was too idealistic to ignore genetic genius and selfishness, and people were unable to hide their greed and became dissatisfied with communism. In the end, communism ended in failure, just like Nazism. Therefore, history shows that it is not right to insist on one extreme, whether it be nature or nurture.
It is an overly deterministic claim to believe that everything is determined by genes. It is true that genes play a decisive role in allergies and physical constitution, and this can influence personality. However, just as innate factors are important, acquired factors must also be taken into consideration. This genetic determinism can be refuted from a cognitive science perspective. Human behavior and thoughts are closely related to brain development, and the human neural network changes more through acquired experiences than through innate factors. When nerve cells are continuously stimulated throughout life, the neural network changes its structure and develops. If such stimulation is lacking in childhood, brain development will stagnate, inevitably affecting personality and character. In other words, even if a person has innate talent, it often cannot shine without the right environment. Furthermore, since the completion of the Human Genome Project, it is difficult to believe that nature has an absolute influence. Genetic determinism cannot be considered correct because the number of human genes is only about 30,000, which is not significantly different from that of fruit flies, indicating that the environment has a significant influence on human diversity. Therefore, it is difficult to believe that genes explain human diversity and personality.
Empiricism argues that genes have only a negligible effect on human diversity compared to experience, but this argument can be refuted by the problem of language acquisition. Empiricism originated with the 17th-century philosopher John Locke, who first argued that humans are born with a blank slate, but the process of language acquisition clearly shows that innate qualities do exist. According to the research of renowned linguist Noam Chomsky, people have a universal language ability that allows them to understand language innately. It is not through acquired effort that we learn grammar, but rather through an innate language device in the brain that helps us acquire language. This is supported by evidence that universal grammatical structures are found in children who speak different languages and that there is a critical period when language acquisition is easiest. In other words, language is acquired through universal grammar that children already possess, rather than being learned from scratch. Therefore, it can be said that, in addition to experiential and environmental factors, innate factors also influence people.
The more similar the innate factors are, the more important the acquired factors become, and conversely, the more similar the environment is, the more important the genetic factors become. This supports the argument that genes and environment are complementary. First, we can see that the more equal a society is, the more important innate factors become. Education is a good example of this. Unlike South Korea, where private education is the norm, most developed countries provide equal public education, but students’ math skills vary. In other words, when placed in the same environment, genes become an important factor in creating diversity. Conversely, the more similar the genes are, the more important the acquired environment becomes. If one identical twin grows up in a happy and stable home and the other grows up in a violent home, their personalities and tendencies will inevitably differ greatly depending on the environment in which they were raised. Identical twins are born with almost identical DNA, but as they grow up, they are exposed to different environments, which leads to differences in their epigenetics. The fact that there is a threefold difference in epigenetics between identical twins at the ages of 3 and 50 shows that even with the same genetic information, slight differences arise through acquired factors. Genetically speaking, mutations in genes can cause acquired differences. The frequency of mutations in human cells is estimated to be about 1/10,000 for a single gene, and since humans have about 30,000 genes, the probability of mutations occurring is quite high, especially depending on the frequency of exposure to radiation and UV rays. As such, we can see that environmental factors also cause differences even when genes are identical.
The most important counterargument to the nature versus nurture debate is that nature and nurture do not conflict with each other in the formation of personality and values, but rather influence different aspects. It has been confirmed that genes have a greater influence on extroverted personality traits, while environmental factors have a greater influence on values and hobbies. This can be seen in studies of identical twins who were separated immediately after birth. In most cases, these twins did not know each other and grew up in completely different environments. They had many similarities, but there were also differences.
First, it was found that genes have a significant influence on a person’s IQ and personality. Identical twins were very similar in terms of intelligence and had similar tastes and tendencies. Surprisingly, they did not resemble the parents of their adoptive families, but rather their biological parents. Genes play an important role not only in physical appearance, but also in mannerisms and extroversion. This shows that genes influence a person’s tendencies by limiting physical factors. On the other hand, experience and environmental factors have been found to contribute to the formation of values. The twins followed the religion of their adoptive families and were found to have values closer to those of their adoptive parents than their biological parents. In other words, environmental factors and education influence aspects that are separate from genes. Furthermore, even if two individuals are born with completely identical genes, as mentioned earlier, strictly speaking, it is difficult to consider them biologically identical because different epigenetic factors occur. Therefore, rather than viewing nature and nurture as opposing concepts, we should view them as influencing each other and contributing to the formation of personality.
Accordingly, we can see that nature and nurture are not dichotomous concepts but interacting factors. As research on genetics and the acquired environment has progressed, modern scientists have come to recognize that neither factor alone is responsible for personality formation, but that both factors influence it. Just as genetic information influences IQ and experience plays a major role in shaping values, nature and nurture depend on each other in the process of personality formation. When natures are similar, nurture becomes more important, and when nurtures are similar, nature becomes more important. Therefore, the debate should no longer be about nature versus nurture, but rather nature via nurture. This will help us avoid political and social problems such as eugenics, which stem from deterministic thinking. Although not yet fully understood, the complementary concepts of nature and nurture clearly have great power in analyzing human behavior and thought. If we can understand the principles and extent of the interaction between these two concepts, our understanding of human diversity and personality formation will greatly advance.
