|SocialismToday Socialist Party magazine|
Issue 229 June 2019
Pre-programmed at birth?
The degree to which DNA determines our lives impacts on a wide range of often controversial issues. JUDY BEISHON reviews a widely-referenced new book looking at some of the key questions in this important, ongoing discussion.
Blueprint: how DNA makes us who we are
By Robert Plomin
Published by Allen Lane, 2018, £20
Following decades of research, psychologist Robert Plomin, a professor of behavioural genetics at King’s College London, has concluded that our genes are the most important factor in who we are as individuals. For a long time the research was based on twin and adoption studies. Identical twins – who have the same DNA – brought up in different families were studied. Non-identical twins and other adopted children were also looked at to see how their characteristics compared with their birth and adoptive families.
Drawing on the results of many of these projects, Plomin says that DNA accounts for about half of the psychological differences between people, the rest resulting from environmental influence. Recent years have seen the rapid development of genetic research at another level: analysis of the genomes, the genetic makeup of individuals. This has opened new pathways for expanding knowledge.
It is worth stressing that we are all 99% the same in our genetic makeup. So it is an understatement to say that, genetically, we have much more in common with each other than not. Regarding the 1% of gene differences, needless to say these influence physical characteristics like eye colour and other aspects of appearance. More obscure is how far they affect the workings of our brains and what the significance of that is for us as individuals and for society as a whole.
Plomin argues that all psychological traits show "significant and substantial" genetic influence. In the case of complex traits, this influence is caused by thousands of DNA differences each having an "extremely small effect size". It has also been shown that genes multitask, so "each DNA difference affects many traits". Some of Plomin’s detractors have distorted or misunderstood his message as ‘genetic determinism’. It does not help that his book is inappropriately titled ‘Blueprint’, but Plomin stresses that "genetic influence means just that – influence, not hard-wired genetic determinism". He reassures readers: "You can beat the genetic odds".
If half the differences between us are environmentally caused, what are their main sources? Surprisingly, Plomin says that all the research has been unable so far to find any family background-based or other systematic source of these differences. So he believes that their origin lies in what he calls the "non-shared environment" and that they are random, chance experiences. He also says they are inconsistent across time: "No identical twin differences have been shown to be stable over several years".
Overall, he is far too dismissive of these environmental effects, despite recognising that they are not yet understood. For him they lack useful meaning so he places an unbalanced emphasis on the importance of DNA for our behaviour and traits.
From a Marxist point of view it seems likely that some of the ‘non-systematic’ environmental influences referred to by Plomin are largely shared by most of us in any given society at any particular stage in history. For instance, they would have been different in a hunter-gatherer or feudal society, and are likely to be different today in economically developed capitalist countries in comparison to less developed economies.
Material conditions, and whether and how basic needs are met, inevitably affect psychology and personality. Hunter-gatherers organised cooperatively and without the inequality of a class structure, conditions which would not have fostered the feelings of individualism, alienation and inadequacy commonplace under decaying capitalism today.
Most of the studies drawn on in Blueprint were conducted in the US and European countries and the same statistics would not necessarily be replicated everywhere in the world. One example given is that a genetic propensity to put on weight shows up more clearly in western countries probably because junk food is more at hand, compared to countries where it is less so. The research also faces other limitations. For instance, it has tended to focus on traits and behaviour that are measurable in some way – in order to be able to make comparisons – rather than assessing hard-to-measure mental states like stress, satisfaction or happiness.
Family and upbringing
Plomin points out that much of what people believe to be behaviour resulting from upbringing by parents and shared family experience is, in fact, due to genetic influence, because offspring are 50% genetically similar to their parents and siblings. Another complication when trying to disentangle nature and nurture is that there is a genetic component to how parents treat their children – a child’s behaviour and characteristics affect the parenting. "Children actively select, modify and create environments correlated with their genetic propensities" writes Plomin.
Socialists must qualify this by adding, ‘to the extent they can’, because in capitalist society most people – children included – are limited in their ability to choose their environments by a lack of opportunity to do so. Plomin grossly underestimates this side of the issue, arguing that "to a large extent, opportunities are taken, not given". Clearly, we do create our own experiences up to a point, but he skirts over the environmental effects emanating from the type of society we live in, absurdly saying: "Beyond the systematic and stable force of genetics, good and bad things just happen".
The genotype-environment correlation has still more complications, as the book points out, because the effect of any particular environmental factor varies depending on an individual’s genes. For example, children who are bullied are affected by it in different, genetically-influenced ways, as well as through environmental influences.
As the vast number of studies has not proved any substantive correlation between an overwhelming majority of psychological traits studied and various aspects of our upbringing, behavioural geneticists have concluded that genetic influence outweighs the environmental influence we have had from our upbringing in a family.
Plomin goes further on this than some: "We would be just as similar to our parents and our siblings even if we had been adopted apart at birth and reared in different families". This goes against what most of us have presumed, and also the basis on which psychologists and psychiatrists have based their clinical practice historically. Parents of offspring with psychological problems may well feel some relief at Plomin’s conviction that, although parents can make a difference to their child, when extreme cases of abuse are excluded, on average they do not determine their child’s future life, traits and happiness.
While psychologists differ on the degree to which this is true, some of the points Plomin draws out seem to have merit, such as the need to "recognise and respect" children’s genetic differences, and that "parents should relax and enjoy their relationship with their children without feeling a need to mould them". He also hopes that all of us will have "greater acceptance and enjoyment of who we are genetically", and that we can "try to go with the grain of genetics rather than fight against it".
Diagnosing ill health
There are many known single-gene disorders that have a determining effect, like the one causing Huntington’s disease. Regarding mental health conditions like autism, major depressive disorder or schizophrenia, however, Plomin outlines that – in common with other psychological traits – they are affected by a great many genes and we all have DNA differences that can contribute towards them. There is no dividing line between people with one of these conditions and those with less serious symptoms of it. Rather, the "abnormal is normal" and the issue is how many of the relevant DNA differences we each have.
In reality, therefore, they are not ‘disorders’ at all, but ends of a spectrum everyone is on. It can be a problem to be at the opposite end of the spectrum, too. For instance, acute anxiety might be at one end but a slow response to danger at the other. On this, Plomin does place some weight on the environment: "Inherited DNA differences contribute substantially to your risk of being anxious or depressed but they do not specify whether you will be diagnosed as anxious or depressed. Whether you become anxious or depressed is caused by environmental factors".
The human genome was first sequenced just 15 years ago, after a decade of work by hundreds of scientists costing £2 billion. Now it can be done in a day for under £1,000. However, a relatively new way of looking at psychological traits is through even cheaper ‘polygenic scores’. Rather than whole-genome sequencing, these enable individual scores to be given for the likelihood of certain traits. This is possible after analysing a blood sample for subsets of many DNA differences that have been associated with them.
So far this method has only been able to estimate a small part of the genetic variance involved. For schizophrenia, for instance, polygenic scores at this stage can only predict 7% of the variance of the liability to be diagnosed as having it. Plomin explains that the percentage will improve as the method is further developed. Nevertheless, he argues that this scoring is already more predictive than any other previous risk-prediction methods, including family history, and can be used for a wide range of conditions.
He suggests it can be used in clinical psychology to help prevent ‘disorders’ from arising and, when they do, in helping to tailor treatment to the individual. However, other psychologists criticise aspects of Plomin’s conclusions on polygenic scores and genetic influence. Among them is Eric Turkheimer, a University of Virginia professor, who has commented that the scores, "although estimated in the genome, are not essentially genetic". Rather, they are "a summary of genetic correlations of all associations, genetic or environmental, immutable or controllable" with the trait being considered.
Also controversial are Plomin’s views on one of his specialisations, educational achievement. He states in Blueprint: "More than half of the differences between children in how well they do at school is due to inherited DNA differences". Further: "If all children are taught the same, their genetic differences would still lead to differences in their achievement".
No doubt for some people it could be a relief to be told that there is a genetic reason why they struggle to do something. At the same time, most of us would consider any assertion that children are fated by their genes to do less well overall as wrong and abhorrent. However, as well as examining the research methods and assumptions Plomin has applied, it is necessary to consider what the capitalist education system regards as ‘achievement’, as his studies are based on that.
Children are usually subjected to rigid curricula and tests that only really assess how well they do in those particular examinations and tense test conditions at a particular time. As we all have genetic variation in psychological traits and personality, these one-size-fits-all assessment methods are not going to suit everyone in the same way. There will inevitably be some degree of genetic variation in the ‘achievement’ measured.
Plomin claims there is a high genetic element in children’s performance in the UK Year One phonics test. This might be an additional reason to change or abolish it – researchers from Leeds Beckett and Newman universities have reported that the test is opposed by most teachers and parents, for a variety of reasons. Either way, having an idea of the degree of genetic effect on any test results does not provide information on how much difference environmental intervention by schools can make on the performance of individual children.
Also interesting to teachers will be that polygenic scores have predicted 11% of the variance in GCSE results, whereas school evaluations like those done by Ofsted have only predicted 2%. Plomin’s stance is not that of the reactionary right. In a previous book, G is for Genes, co-authored with Kathryn Asbury, he called for a reduced national curriculum, more freedom for teachers and an individual education plan for every child, among other welcome demands.
If polygenic scores were to be used to predict a child’s susceptibility to learning difficulties, he wants that information to be used to enable steps to help that child. Yet Turkheimer has pointed out potential dangers with that kind of early intervention. It opens the door to giving specialised help based only on a child’s propensity to have difficulties which, he argues, would be "biologically determinist discrimination". Turkheimer also takes issue with another of Plomin’s controversial arguments: that parent-offspring resemblance for educational attainment primarily reflects genetic influence, not environmental inequality.
The criticism of measures for achievement can also be applied to intelligence tests, which show genetic variation as well. Genes clearly have influence on traits often associated with intelligence, such as memory, verbal skills, numerical concepts, spatial awareness, speed of thought and so on. But there is no agreed definition or measurement of intelligence. In reality, there are many different leanings to it, which might manifest in an analytical, linguistic, emotional or musical direction, to give a few examples, with no dividing lines between them.
Moreover, the skills and aptitudes that have been most important to society have changed over time, depending on the type of society and the level of the means of production. Genetic studies on the variation in IQ (intelligence quotient) are based on a limited range of cognitive skills, usually assessed under time pressure at a particular time.
Rather than assessing people as inherently more or less ‘intelligent’ or ‘bright’, as do Plomin and many others trained in capitalist academic institutions, there should be recognition of the full diversity of human thought processes without placing them in any order of merit. A socialist education system would value and nourish all talent and abilities instead of marking young people as successes or failures based on narrow criteria.
Inequality and social mobility
Plomin does castigate inequality and wants to see a ‘just’ society where all jobs provide the means for a reasonable standard of living. He does not believe that what he views as higher ‘intelligence’ merits more income and he raises the reformist demand that income inequality could be reduced by a tax system that redistributes wealth. He makes interesting comments about privilege and social mobility, arguing that "greater reduction in environmental inequalities of privilege, wealth and discrimination will result in greater heritability of educational outcomes", ie a bigger genetic component to educational outcome.
Addressing this from a Marxist viewpoint, we could say that in a socialist society – with the development of real equality of opportunity and an end to privilege and discrimination – working-class and middle-class people would be able to realise far more of their potential than they can under capitalism. This would be possible through public ownership of the companies that dominate the economy along with socialist planning, providing the basis for all material needs to be met. We could choose to ‘go with the flow’ of our genes, exploring our talents and interests, and success would not be measured by narrow criteria and money-making but by using our aptitudes to enrich our own lives and the whole of society.
In this higher form of human society it seems possible that heritability would be higher in each field of activity (artistic, mathematic, empathic or any other) than it is in capitalist society, where individual talent, effort and merit is often blocked by poverty and lack of opportunity. But it is not possible to predict the extent of the rest of the equation: the impact under socialism of a massively transformed environment – which need not be at all uniform – on gene-environment interaction and what that will open up for us as individuals.
If people do eventually gravitate more towards the jobs in society that most suit their genotype, the points made by Plomin indicate that this would not lead to the development of ‘genetic castes’, because of the extent to which parents have genetically different offspring.
Dangers from the right
Right-wing politicians sometimes misuse studies on genetic influence to justify policies of discrimination, inequality and public-service cuts. In 2013, Boris Johnson odiously claimed that human beings are "very far from equal in raw ability" and that inequality is essential for the "spirit of envy" and "greed", and is "a valuable spur to economic activity". That same year Dominic Cummings, an advisor to the then education minister Michael Gove, wrote a paper drawing partly on Plomin’s research. The Guardian reported that Cummings "proposed genetic screening to identify those capable of the scientific innovation needed to compete economically against rising Asian powers". Theresa May has advocated having more selective grammar schools, using genes-based arguments of promoting merit rather than privilege.
Available for the far-right has been highly discredited genome arguments like those cited in books like The Bell Curve, authored by Charles Murray and Richard Herrnstein, which made abhorrent racist claims about intelligence. Also vile would be any resurgence of eugenics arguments: discouraging the reproduction of traits deemed undesirable, as was done horrifically by the Nazis, or through the forced sterilisations carried out in the US and Canada in the 20th century. There are also fears in other respects. Employers or insurance companies could try to use polygenic scores to discriminate against people, in order to boost profits.
How polygenic scores could be used on babies or even embryos is an issue, too. In IVF, embryos are already screened for chromosomal abnormalities but most people would no doubt oppose ‘designer babies’ being selected on polygenic scores for their psychology. Newborn babies are already genetically screened for phenylketonuria (a rare inherited disorder) and can be for other single-gene disorders, but what if parents buy polygenic scores on their baby’s possible behavioural future? That raises the danger of creating self-fulfilling prophecies or making unwarranted early interventions.
It also raises the issue of the future privacy of the individual being tested. Plomin comments: "Polygenic scores represent a major scientific advance and, like all scientific advances, they can be used for good as well as bad". In any case, he says, "the DNA revolution is unstoppable… millions of people have already voted with their credit card by paying to have their genomic fortunes foretold".
Certainly, knowledge is advancing rapidly in this field and Blueprint is an important and interesting contribution to the discussion on the issues thrown up. Overall, while many caveats and qualifications must be kept in mind when assessing genetic research and its conclusions – and there is an enormous amount yet to be discovered – the developments are providing new ways of gaining greater scientific understanding about human populations and individuals.
Socialists, however, can agree with Plomin’s point that "no specific policies necessarily follow from genetic findings, because policies depend on values". A socialist society will not only be able to accelerate the advancement of scientific knowledge but will lay the basis for democratic decision-making on the best use of that knowledge for the benefit of all humanity.