Which one comes first, nature or nurture?

Nowadays, when we think about IQ, we think about tests as serious as those taken in kindergarten or as casual as those on Facebook. The results of these tests are an important indication of how smart we are. We would like to think that intelligence is genetic, which in a way means that we were born with our IQ. In The Agile Gene, Matt Ridley mentions that researchers have found that brain size and volume of gray matter are correlated with intelligence. Thus, the scores of our IQ tests seem to be really the result of heritability.

Does this downplay the role of environment? In our real life, we can find evidence that environment contributes equally significantly as genes. In the US, schools try hard to make the situation even for children. Children are trained in a way that intelligence does not influence performance in a significant way. Just imagine what score you can get if you take SAT or GRE eight times.

However, Ridley raises an interesting point. He demonstrates that in childhood, the environment including school and family can influence intelligence, but in adulthood, when one leaves the environment where one grew up, this influence diminishes and intelligence is again mostly genetic. From this point, Ridley concludes that adults create their own environment, which children cannot. Adults look for environments that can satisfy their appetites, but children live in environments chosen by others. Therefore, our ability determined by our genes controls our appetite which encourages us to do what can satisfy our need.

My question is: do we really have the freedom to choose what to eat to satisfy our appetite? Our culture now generally values intelligence. Higher education is a goal adopted by most people. Seeking high education is not what our genes tell us, but it is rather a cultural value that influences all of us, not to mention some relevant social factors. For example, the beginning salary of people with a Master’s degree is higher than those with a Bachelor’s. Therefore, going to graduate school does not necessarily justify the mechanism described by Ridley.

Ridley also argues that personality is heritable. He mentions a twin study by Bouchard about fundamentalist individuals. As we all know, religion is a social construction, which is a cultural thing. Bouchard gave questionnaires to participants and measured the correlation. He found that the correlation scores for identical twins reared apart are 62% while that for fraternal twins are 2%. Ridley explains that religiosity is one attribute of personality. Thus, people with certain religiosity are more likely to become fundamentalist. Does this view not dramatically simplify the nature versus nurture debate? That people are really programmed to have a tendency to believe in something reduces the variety of people in some way. Similarly, culture plays a big role in religion as well as personality. If the theory of religiosity holds true, it probably means that certain cultures favors a particular religion, in the same way that certain cultures favors a particular personality. Susan Cain in her Tedtalk claims that US culture encourages “extroversion”; it emphasizes “action” more than “contemplation.” In school, class is designed in a way that fits more extroverts. Group work is really important that even subjects such as creative writing and math require group activities. Thus, children can be trained to be social, outgoing and extrovert. According to her, culture seems to remarkably influence personality.

Therefore, in real life, nurture seems to be more crucial than nature, given that culture and society define ideal behaviors. Ridley gives another interesting theory of meritocracy. He argues that if the environment is the same for everyone, meritocracy is achieved because only genetic variation determines people’s ability, thus most intelligent people are those with best genes, and most extroverted people are those with most extroverted genes. Nevertheless, this is merely a theory because in reality, the environment cannot be equal for everyone.




Cain, S. (2012). The Power of Introverts. https://www.ted.com/talks/susan_cain_the_power_of_introverts?language=en

Ridley, M. (2003). The Agile Gene. New York, NY: Harper Collins Publishers Inc.

Waller, N.G., Kojetin, B.A., Bouchard Jr, T.J., Lykken, D.T., & Tellegen, A. (1990). Genetic and Environmental Influences on Religious Interests, Attitudes, and Values: A Study of Twins Reared Apart and Together. Psychological Science, 1(2), 138-142. doi: 10.1111/j.1467-9280.1990.tb00083.x


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