Robert Plomin and the importance of genes

Professor Robert Plomin is a researcher at the Institute of Psychiatry, Psychology and Neuroscience, King’s College London.  In 2018 he published a book, Blueprint, which reveals his research findings.

He looked at the genes and life-histories of 10,000 twin pairs born 1994-6, some of whom were identical, some not, some brought up by the same parents, some not.

In recent years we have seen large scale availability of genomic data from significant numbers of individuals. Scientists now know that the genetic influence over our personalities arises from thousands of tiny variations in our DNA, rather than one or a few genes alone. So, most traits are “polygenic”— that is, influenced by many genes. This multitude of differences makes each of us genetically unique (unless you are an identical twin).  The tiny DNA variations are called “single nucleotide polymorphisms” or SNPs.

Plomin believes that he has shown:

1 Genes become more significant as you get older because you create and select your own environment according to your genetic propensities.  Slight nudges from genes early on are amplified as time goes by.  So, for example, children with a high IQ are more likely to read books.

This is why we become more like our parents as we age.  We become more who we really are.  As children get older genes become more important.  So a child labelled as able when 5 may not be so able when 16.

Parents teach small children to read so they are more important than genes in determining your ability to read when young.   But once all children go to school, the impact of school on VARIATIONS in reading ability become less due to school and more due to genes.  The better an education system, the more significant genes become in determining gaps in achievement.

So in the year 1800 there was a nationally low level of reading.  Genes were less important explaining VARIATIONS in outcomes than environment (parents, whether you go to school).

Now we have a nationally high level of reading. Genes are more important explaining VARIATIONS in outcomes than environment.

2 Genes are more important than the environment.

Genes explain 60% of differences between individuals in school achievement, the environment explains 40%.  BUT the influence of the environment is mediated through genes.  When he looked at the KS1 phonics test he found variability was 70% due to genes – not teachers.

Note that when he says ‘heritability for weight is 70%’ he does not mean your weight is 70% down to your genes, he means that 70% of the differences between individuals across a population is down to differences in DNA.

School attainment is now better forecast by a polygenic score than any other way of predicting it — it is better than knowing how the parents did at school, better than socio-economic status, better than the type of school.  Our families and schools account for less than 5% of differences between us in terms of mental health or how well we did at school once we control for the impact of genes.

Most measures of the “environment” show substantial genetic influence because people adapt their environment better to suit their natures. For example, Plomin discovered that the amount of television adopted children watch correlates twice as well with the amount their biological parents watch rather than with the amount watched by their adoptive parents.  Children respond differently to the opportunities presented by school, and this is in part genetic.

Remember that our children are 50% genetically different from us.  Able parents do not all have able children – your children are only 50% the same as you genetically.  So if your parents have a high average IQ of 130 their children will on average regress halfway to the population average (100) = 115.   Similarly, average parents can have bright children.

Incredibly, Plomin concludes that children growing up in the same family are no more similar than children growing up in different families, if you correct for their genetic similarities.  If you were cloned and your clone was raised by another family, went to another school, they would still be very similar to you.

Gene scores predict the mean outcome for groups but there is a wide range of individual differences within each group.   So you have low ability genes but you can do well in GCSEs.

The most highly heritable trait is vocabulary.  This is led by genes.

3 The most important environmental influence is chance, not school or family.  We are more influenced by accidental events of short duration such as people we meet than by family.

4  IQ does not correlate that well with achievement.  So motivation is also vital as well as self confidence.

General intelligence accounts for 25% of the variance in educational achievement.

Genes are not destiny…you can change eg lose weight.

If you have a low polygenic score for academic ability you just have to work harder.

There is no genetic difference between boys and girls in terms of science ability.

He thinks that if children are to be enabled to fulfil their potential, then you cannot believe that they are the product of their upbringing or education. You must understand that they have innate aptitudes that can overcome environmental disadvantages. Nothing, he believes, is bleaker than environmental determinism.

5 All schools and all parents are quite similar now so…

‘If you make equal opportunity happen, what you are left with are the genetic differences’.

The educational benefits of selective schools largely disappear once the innate ability and socio-economic background of pupils at selective schools are taken into account.  Pupils attending grammar and private schools have significantly higher genetic scores for academic ability than those in comprehensives.

6 Meritocracy and social mobility

What does this mean for social mobility? On average children from low SEGs have lower academic ability BUT the range is quite wide so there are many exceptions.

On the other hand assortative mating is rising (people are more likely to marry someone similar to themselves) and this means that the gap is growing in terms of the ability of children from two able parents and those from two less able parents.

All should have equality of opportunity, but that will not mean equality of outcome.  Equality of opportunity means that genes determine outcomes.  All social mobility proponents are in reality trying to do is reduce the impact of the 20% home/school environment differences

Schooling should be a chance to discover what your genetic self is – what you like.

Schools will not solve inequality.  Taxes do that.

In summary

60% of academic ability can be predicted from your DNA, 40% from environmental influences.  However, environmental influences are not what we think…they are less to do with the family and school, more do with random events, such as people we meet.  Furthermore, many things which APPEAR to be environmental, such as your mother reading to you, turn out to have a genetic basis – your mother is more likely to read to you if she senses you enjoy reading, and enjoyment of reading is genetic.

What does this mean for individuals?  DNA is not deterministic.  You may be genetically programmed to be overweight, but that simply means that you have to eat less and exercise more.  If you do so, you will not be overweight.  So hard work to counter the influence of your DNA is the key.

What does this mean for schools? There could be a lot to be said for identifying an individual child’s genetically-generated strengths, weaknesses and interests and using that knowledge to build on known strengths and interests or to counter weaknesses.

Plomin’s research does not mean schools make no difference.  We can make a big difference, even if we go against the flow of the DNA.

In the near future parents will have the genetic code of their children.  The code can be determined at birth and does not change.  So we may come to learn more about the children in our care, for good and ill.

What is he planning next?

A study of 1.1 million people has produced a polygenic score (EA3) that can predict 15% of the variance in school performance at age 16.  His aim is to test the hypothesis that EA3 can help to widen participation in higher education by targeting interventions on disadvantaged pupils with high EA3 polygenic scores. He will obtain DNA and create EA3 polygenic scores for 10,000 Year-7 (12-year-old) pupils from disadvantaged environments. He will identify 500 pupils with the highest EA3 scores and randomly assign them to experimental and control groups, and the same for 500 pupils with mixed EA3 scores. The experimental groups will receive an intensive widening participation intervention throughout secondary school that will pave their way towards degree-level careers. He will compare the educational trajectories of the experimental and control groups to test the hypothesis that we can improve the life chances of children with high EA3 scores.

To many of us the Plomin research seems disturbing at the very least.  But if he is right, that gene-mapping will become commonplace, it is worth keeping an eye on him.

Professor Barnaby Lenon, Dean of  Education

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