DNA: The Influence of Genetics in Learning & Development

On the 9th May 1960 the US Food and Drug Administration approved the contraceptive pill for general use, triggering what has since become known as 'the sexual revolution'. Although 'The Pill' was not widely used by young single women until the mid-1970s, the general increase in sexual promiscuity led to a significant rise in the percentage of babies born to unmarried mothers; from less than 4% of births in the late 1950s to in excess of 15% in the early 1970s.

Abortions were not legally available in the US until 1974 and it was still considered socially unacceptable for unmarried women to become pregnant, especially in religious communities. The net result was that there was a boom in the number of babies being put up for adoption, which in turn created a fantastic research opportunity for a young psychologist by the name of Robert Plomin.

Having recently completed his PhD, Plomin secured his first academic job at the University of Colorado with joint appointments in the Department of Psychology and the Institute for Behavioural Genetics, and decided to initiate a long-term adoption study of psychological development. More precisely, his interest was in studying the influence of both nature and nurture on psychological development.

In this context, 'nature' refers to the traits and features we inherit from our parent's DNA, while the word 'nurture' refers to the influence our environment has on us as we learn, develop and grow.
The influence of genetics is obvious and undisputed in our physical appearance, but ever since psychology became established as an independent subject of study, it had been assumed that psychological traits were caused by environmental factors. These environmental factors were labelled 'nurture' because, from Sigmund Freud's work onward, their origins were thought to lie in the family environment. In other words, because these traits run in families, it was assumed that it was the family environment that was responsible.

To test this, Robert Plomin set up what has become known as The Colorado Adoption Project. The objective was to track adopted children in 250 families, where those children had been separated from their biological parents at a very young age, and to compare them to children in 250 other families where they grew up in the same home as their biological parents.

In addition, a third of the adoptive families adopted a second child, so Plomin was also able to compare children with different parents growing up in the same family environment.

The study was initially intended to run for a few years during early childhood. However, it was so successful that it is still running today, with the oldest subjects now being in their 40s. The results have been described in 4 books and over 150 research papers.

Their major finding, which has since been corroborated by numerous other research studies, is that DNA accounts for 30-60% of most psychological traits, and that on average, nature accounts for 50% of who we are. In other words, Freud was wrong!

In many ways, the discovery that nature is every bit as influential on a person's psychological make-up as nurture is unsurprising as our brains develop from the same single cell as the rest of our bodies - and no one has ever suggested that the reason children look like their parents is because they grew up in the same household.

Looking at the findings of the Colorado Adoption Project in more details, we find a strong correlation in areas such as eye colour (95%), height (80%) and weight (70%), but the most surprising finding is the strong genetic predictability of psychological traits such as academic achievement at 60% and general intelligence at 50%1.

Does this mean that teachers and trainers are all wasting their time? That learning outcomes are preordained by the genes a person inherited from their parents?

The answer is 'no', for the simple reason that while genes can explain where we come from, they are not our destiny. Genetic coding affects the probability of outcomes across groups of people, it does not determine the psychological outcome for any individual. For example, there is no gene that means that if your parents got first class honour degrees from Cambridge, that you will automatically receive one too! Instead, thousands of genes are involved in traits such as tenacity, reading ability, enthusiasm for study etc. If you have a high number of these types of genes and associated traits, academic study is likely to be easier for you than if you had less of those genes.

The genetic 'fingerprint' you inherit from you parents therefore influences where you come from and the way in which your energy and motivation will be directed.

This is of interest to me as my own work has been in understanding the ways in which our physical brains make us the person we are. In the same way as we know that 99% of the 3 billion rungs in the DNA sequence are identical across all humans2, our physical brains are also remarkably similar - yet we all turn out as unique individuals with our own thoughts, dreams, skills and ambitions.

I often use a colour printer as an analogy to help explain this remarkable transition from similarity to individuality. Imagine a printer, with its four toner cartridges, as being like the physical brain. Each printer contains the same cyan, magenta, yellow and black toner cartridges, yet it is possible to print an infinite variety of colours and an infinite variety of different pictures from the same standard components.

The human brain is much the same. We all have the same physical structures in our brains and the same processing capabilities and styles, yet we all mix them in a unique way through the trillions of connections established by our synaptic network. Some of those connections will have been predetermined by the DNA we inherited from our parents, while others will have developed as a result of our own learning and experiences.

The way in which the relatively standard physiology of human brains can result in the enormous variety and complexity of human psychology has been a long-term fascination for me, so in 2003 I joined forces with my colleague Gill McKay to see whether it would be possible to identify and explain this boundary between physiology and psychology.

To aid our research we developed a questionnaire that we called a 'Neurometric' - 'neuro' because it was based on a neurological model of the brain, 'metric' as it was designed to assess a person's preferences against our theoretical framework that sought to explain the causal relationship between the brain's physiology and a person's psychology.

The results were so effective in helping people understand the reasons why their own energy and motivation were directed as they were, and why other people's energy and motivation may be directed differently, that we decided to make it available to a wider audience. In 2007 we launched MyBrain International as a company dedicated to training people in what we now call the MiND Instrument, so that they could use it in their own training and coaching work to help individuals, teams and even whole organisations improve their performance.

Since then, numerous individuals have been trained as Practitioners and I am proud and delighted to say that the feedback from them and the individuals and organisations they have worked with has been outstandingly positive. Simply put, the MiND Instrument helps people deliver better results.

If you would like to learn more about our work, or if you would be interested in becoming a certified MyBrain Practitioner in Applied Neuroscience for People Development, please get in touch.

1Blueprint: How DNA makes us who we are, Plomin, 2018, p6
2Ibid p112

Family image courtesy of all-free-download.com

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