Nature versus Nurture

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The nature versus nurture debate tries to explain whether our behavior is influenced by the genetic factors or by the environment we live in. Research in biology, neurology, and psychology concluded that both genetic and environmental factors exert a strong influence on our behavior.

Genetics help to explain the similarities that are found among identical twins raised in different families. It helps to explain the differences between two brothers raised in the same family. In this case, differences may be caused by the nature environment.

This idea suggests that up to a certain point we are guided by our genetic structure to search, select, and to create the environment we live in.

To better understand this idea, I will present the behavior of two brothers, John and Roger, who live in the same house.

John gets in the living room holding a pack of cards, a puzzle and a book. He starts to solve the puzzle. After finishing the puzzle, John builds a box of cards. Finally, he reads a story from his book.

In the same living room, Roger puts a chair and some pillows on the coffee table. He starts to jump from the chair.

John has created a safe environment, while his brother has created a dangerous one. It seems that, besides the fact that they both have the same genetic construction, they have created a very different environment.

When we talk about the nature of the environment, we think at the education received from parents, their behavior towards children. For example, if a child likes to be hugged will get more hugs from his parents than his brother who is cold and distant.

Research has shown that at birth, each of us comes into the world with temperamental predispositions.

According to psychologist Jerome Kagan, 20% of us are born with a physiology so easily excited, so sensitive that anything unfamiliar appears as a threat. 40% of us are born with a much less exciting physiology and as a consequence we are more relaxed. Starting from these predispositions, people will develop a certain temperament that will influence the most part of the decisions they will make. (Jerome Kagan was born in 1929, he was ranked 22 in the list of the most eminent psychologists of the 20th century).

Other studies on alcoholism, depression, drug addiction and schizophrenia highlighted the influence of genes. For example, a study in Denmark revealed that 22% of biological children of criminal fathers become criminals, though they have grown up with a stepfather who had no criminal records. The same study showed that if the stepfather is a criminal and the biological one is not, only 11.5% of the children become criminals. This study shows the existence of a strong link between genetic construction of people and criminality.

Although we accept the idea that genetic factors have a strong influence on our behavior, we can’t believe that people are just the sum of biological components. Besides heredity, people are influenced by the environment and personal experiences.

“Humanity cannot be cut adrift from its own biology, but neither is it enchained by it.” (Rose, S., Kamin, L. J., Lewontin, R. C. (1984). Not in Our Genes: Biology, Ideology, and Human Nature. New York: Pantheon Books)


Rose, S., Kamin, L. J., Lewontin, R. C. (1984). Not in Our Genes: Biology, Ideology, and Human Nature. New York: Pantheon Books

Viorst, J. (1999). Our Lifelong Struggles with Power and Surrender. New York: Fireside - The Journal of Undergraduate Neuroscience Education, Spring 2004