Nature versus nurture: Questioning a cornerstone of psychology

The concept of nature vs. nurture is one of the cornerstones of psychological theory and research. In fact, some human development textbooks use nature-nurture as a central theme. Nature vs. nurture goes back to the times of Sir Francis Galton, who first used the phrase in 1869. Galton was without question one of the brightest minds of his time; he developed early forms of regression and correlation in his quest to show that genius and other human traits were inherited. He was related to Charles Darwin, after all.

It seems to roll off the tongue: “nature versus nurture.” And the idea forces the mind to hold two ideas simultaneously, perhaps even to consider their interaction. [It is difficult to hold two ideas in our minds, have them interact conceptually, and simultaneously consider others.] The concept has become so ingrained in our thinking that most psychologists believe that nature-nurture is an established fact. A well-respected scholar and former president of the American Psychological Association, Robert Sternberg, noted that “nature and nurture are unitive,” that is, they add to one.

In fact, the studies of nature vs. nurture are considered to be a gold standard of research methodology: identical twins (who have identical genetics) are studied. By comparing identical twins raised together (identical environments) with those separated at birth and raised apart (different environments) we have a clean way of comparing the two factors. A related method is to compare fraternal twins (genetically as similar as any brother or sister) with identical twins raised together (each pair is assumed to have an identical environment). In order for the statistical tests to be valid, it is necessary for only genetics and environment to control human development for any trait studied. So Sternberg’s statement of unitivity is a central assumption of all of our twin studies of nature vs. nurture.

Nature vs. nurture. So… which one is responsible for intelligence? For language development? For musical ability? For alcoholism? For depression?

Note, however, that there is an assumption hidden in each question: we must conclude that it is nature or nurture (or both) that shape us. If we examine the assumption of unitivity carefully, that nature and nurture add to one, it requires that nothing else is responsible for our development. Now that’s a big assumption. In other words, for any trait studied, we are assuming that genetics and/or environment are the only factors that contribute to who we are.

The problem is, no one has ever demonstrated that nature and nurture alone control human development. The professions of counseling and psychology assume that each person has some small area of choice, some ability to change. If that were not the case, then there would be no justification for therapy.

Viktor Frankl, who spent years in some of the worst concentration camps during World War II, noted that everything can be taken from a person except one thing: no matter how desperate the situation, each person can choose his or her attitude toward an unalterable fate. Fate: that’s what happens to us. Nature and nurture are our fate. Because we have no control over our fate, we are not responsible for it; we are only responsible for the attitude we choose toward it!

One example cited frequently by nature-nurture experts (including Sternberg) is phenylketonuria (PKU). A century ago, some babies were born normally, but soon began to stunt in their growth and mental development, and usually died quite young. About 50 years ago, a doctor noticed an odd smell in the urine of a baby, and discovered that ketones were present in excess in the urine. (Ketones give bananas their smell, for example.) He deduced that the smell of ketones resulted from the inability of the body to break down phenylalanine, an amino acid normally present in the body. Simply by eliminating foods with phenylalanine, the babies were able to develop normally. This is used as an example of nature (the genetic inability to process phenylalanine) and its interaction with nurture (the ability to change the environment to produce health).

This is an important example that clearly illustrates nature vs. nurture. But hidden within the example is a third factor, a uniquely human dimension. Human beings have developed the scientific capacity to investigate these problems and discover solutions, and we have the ability to transmit this knowledge to others. Most important is that each person has the freedom to be tested, and the free will to choose to follow the diet. If this choice were not made (admittedly by the parents) then the child would likely not survive.

So a third factor that affects human development would be the person’s free will, the ability to choose, and the ability to reason and have insight. As I have noted in American Psychologist, Galton’s biggest assumption was that the human being is an automaton, a helpless victim of nature and nurture. If the person is solely determined by genetics and environment, then is choice truly possible?

In fact, Galton’s very assertion of nature and nurture is an example of the human capability of transcendence of thought. How could genetics and environment, even in interaction, explain his brilliant insight: that nature and nurture are important factors of human development? The very fact that we can have a discussion about nature and nurture is evidence that the human being is capable of overcoming the fate delimited by them.

Frankl put forth that the human being lives in three dimensions: soma, psyche, and the noëtic. Soma is the physical, concrete dimension—our physical body is somatic. The psyche (or psychic) is composed of our intellect and emotions. The noëtic is the arena of the human spirit, of free will, of choice. Viktor Frankl defined the noëtic as that which makes us greater than the animal. So it is in the noëtic dimension that we develop the language of science, music, and transcendence. Arguably, Galton’s idea of nature and nurture is evidence of the noëtic dimension, that part of human life that transcends soma and psyche, which are the realms of nature and nurture. Ironically, his idea, the fact that he thought of these things, is also proof that nature and nurture alone are not sufficient to explain human experience.

Frankl also noted that a person with an addiction to alcohol may have been drinking for 30 years, but he also must choose to take the next drink. It is this tiny area of choice that is the basis for all of the helping professions. It is in this area of choice that our uniquely human dimension lies. And it is in the area of choice, for which we are responsible, that each of us finds hope, meaning, and purpose.

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