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Nature versus Nurture

Some think that the ‘Nature versus Nurture’ debate is an anachronism inherited from the 19th and 20th century intellectual squabbles. They couldn’t be more wrong. The ancient Greeks too debated about it. Our ancestors mused about the same in the Upanisads and the Geeta. The Chinese had a nuanced view of the same and incorporated it in Confucian thought. It seems that wherever great civilizations sprout, the intellectuals of those civilizations debate on the nature of man and the reason for his personality.

We have known for a long time that certain physical characteristics are a function of a person’s genes. These include the nature of hair growth, skin pigmentation, eye color and even a lot of diseases. Some other physical characteristics appear to be significantly influenced by our parents’ genetic make-up.

Data has confirmed the hair loss in men, life expectancy, height , weight as well as susceptibility to certain specific illnesses are positively co-related amongst individuals who are related genetically. A logical extension of this would have been a study of the correlation of personality traits of genetically related individuals. This too has been found to be positively co-related. The personality traits referred to above include behavioural tendencies, IQ, and other personality attributes.

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On one end of this spectrum are those of the Biological approach (also called the naturalists). They hold the assumption that genetics, hormonal and neuro chemical study give the best explanations to personality traits of an individual. Libertarians and conservatives generally tend to hold this approach in high regard.

Some nativists say that every individual has an inbuilt biological clock which switches on or switches off certain types of behaviours and traits in a pre-programmed manner. Those points of switching on or off are known as points of maturation. These behaviours and traits include linguistic traits, ‘Childishness’, affinity to cry and even enhanced cognitive development.

Environmentalists (also referred to as empiricists) are at the opposite end of the spectrum. According to them, the human mind is a blank slate i.e. a tabula rasa which is gradually conditioned by experience and societal behaviour towards an individual.

To summarize the debate- There are two sides , each of whom takes maximalist position in the debate i.e Nature saying that Genes play a more important role than the environment and vice versa.
I first heard about this debate 6 years ago through an article in The Economist (The Lexington Blog to be precise). I had started reading the newspaper a few months ago by then and used it as a tool to learn about interesting topics. This surely was an interesting topic and the article directed me to a book by Matt Ridley (A rather fascinating book in my humble view) and a post by Alex Tabarrock in Marginal Revolution (one of my favourite Economics websites).
Matt had concluded that the Nature versus Nurture debate tended to be a Zero-Sum debate with little space for nuance as according to the latest research in genetics as well as empirical studies, it was evident that contrary to popular notions, Nurture too depends on genes and genes(i.e. nature) depend on Nurture. Genes as he shows not only pre-determine the brain’s structure, but also imbibe formative experiences, memory and also respond through change to social cues. The personality and will are both a cause and consequence of genes.
The post on Marginal Revolution also gave out some interesting statistics on the issue. In a study which analysed the effect of Parental income on adopted children’s incomes, it was shown that adoptees don’t show a positive correlation to rise in parental incomes while non-adoptees showed a clear positive correlation.


If you use income as a metric for studying life outcomes, the data is in favour of nature in this debate. Nurture seems to account for a lot less than what Freud thought it did. As Mark Manson sums up rather pithily in a very readable post on the subject –

‘Freud introduced the idea that parents, through influencing a child’s unconscious, could actually shape how a children see themselves and see the world. Through their actions, parents could actually shape and mold a child’s permanent personality, for better or worse.
The idea intuitively made sense. Although Freud’s explanations for how this actually happened were a little bizarre . Little boys wanted to murder their fathers and (have sex with) their mothers. And little girls were doomed to spend their entire lives secretly wishing they had (male reproductive organs).’

At this point, it is necessary to point out that the studies used to justify, defend and propagate the Nature theory aren’t cross generational studies. To be more precise, they don’t necessarily refute Matt Ridely’s hypothesis that Nurture and genes depend on each other. I’m yet to come across a study which compares the incomes of the children of adopted children with high income parents and also incomes of children of adopted children with normal income parents. The data set of non-adopted children can be used as control. This study might be a good way to test Ridley’s hypothesis.

Mark Manson quite beautifully argues against the Behavioural school and the extension of their hypothesis to the field of parent-children relationship. I would rather call it a minefield. My fellow men and women of my age tend to give ‘Parental behaviour towards them’ as a reason to explain away their various inadequacies and immoralities. I don’t know for sure from where they got this thought but it may be due to their excessive use of American soap-operas. (Acquired behaviour this perhaps! or is this too a function of their genes i.e. a genetic affinity to shift blame!).

He points out (with the help of various studies which uses data from twins separated by birth) that 45% of our personality is determined by genetics and the rest by social influences. The fun part is that amongst identical twins not separated by birth- there is only a 45% similarity!! In short, inconclusiveness at its best!
My personal take on this comes down to my belief in the conclusiveness of some data and inconclusiveness of other sets of data. Since little data in this debate is conclusive in its findings, it is only natural to not conclude on any view as of now!

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