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Kathryn Paige Harden argues that how far we go in formal education – and the huge ripple effects that have on our income, our jobs and our health – are in part due to our genes. Harden is a professor of psychology at the University of Texas at Austin, where she runs a laboratory using genetic methods to study the roots of social inequalities. His provocative new book is The genetic lottery: why DNA is important for social equality.

Even talking about whether there might be a genetic element in educational attainment and social inequalities breaks a huge social taboo – especially on the political left, where you say your own sympathies lie. The specter of eugenics hangs over and no one wants to create a honey pot for racists and classists. To be clear, it is scientifically baseless to claim any differences between racial groups, including intelligence, and you don’t. But why go here?
I first wrote this book for my fellow scientists, who did not necessarily see the relevance of genetics to their own work or were afraid to incorporate it because of these associations. Much scientific knowledge is ignored lest the genius of eugenics emerge from its bottle.

But also people hear about new genetic discoveries every day and see in their own families and lives that genetics matter. When asked to estimate how much genes influence intelligence, people’s responses are not zero. I try to help them make sense of this information in a socially responsible way. If you care about social equality, what do you do with information about genetics?

You have been accused of promoting eugenics, including by a prominent sociologist Benjamin Ruha, who wrote in which you engage “A wise shift between genetic and environmental factors which would be the pride of the founders of eugenics”.
These fears come from a very real place – historically genetics have been misused. Corn [eugenics] is literally the opposite of what I am advocating. The central idea of ​​eugenics is that there is a hierarchy of lower or higher people that is rooted in biology and that inequalities are justified on this basis. Mine is an anti-eugenics approach seeking to use our knowledge of genetic science to develop policies and social interventions that create more social equality. Sweeping genetic differences between people under the rug does not make the genome disappear, as a systemic force causing inequality. That genetic and environmental factors are intertwined at all levels is just a description of reality.

How to predict the level of education of a person via his genome?
It starts with a statistical correlation exercise called a genome-wide association study (GWAS). This takes several hundred thousand people of similar genetic ancestry and measures tiny genetic differences – of which there are millions – scattered throughout their DNA sequences. He then seeks to determine which of these variants correlates with their number of years of schooling.

We then take the results and – for a new person’s genetic sequence – add that information together to produce a single number, a polygenic score, which predicts how far they will go in school.

Although crude, the GWAS approach has found genetic variants that correlate with school pursuit. This is not surprising – we are seeing evidence that there is a genetic influence on academic achievement in twin studies. Identical twins are more similar as far as they go to school than fraternal twins.

How many variations are we talking about and how big is the effect?
Scientists have identified over 1,000 genetic variants spread across the entire genome, each with minimal effect. Taking the combined influence, it captures about 10-15% of the variance in educational attainment. The college graduation rate is almost four times higher for people who have a high polygenic score compared to a low polygenic score. This competes with other variables that we think are important for educational attainment, such as family income, which has an effect size of around 11%. But it’s still lower than the twin study’s estimate that about 40% of the variation in educational attainment is due to genes.

Can we say that differences in educational attainment are caused by our DNA? Correlation does not equal causation and we know the environment makes a huge difference.
We are reasonably certain at this point that the causal genetic influence is not zero. It is the size which is in question. There are questions with the twin studies as to whether they attribute to genes what should really be claimed by the environment. And for studies of polygenic scores, people may just differ genetically in a way that matches environmental factors, and it’s really those that cause the effect.

More confidence in our conclusions comes when we get similar answers with different methods. Studies of polygenic scores within families now also suggest a genetic cause. For example, studies of siblings raised in the same environment, but with more different polygenic scores, show that these siblings have more different life outcomes.

Are people who have these genes smarter?
The word “intelligence” is a lightning rod, for it is so easily mistakenly presented as a marker of all human skill. But it is clear that formal schooling in the United States and the United Kingdom reinforces a very particular type of reasoning. And this is the same type of reasoning that IQ tests also take up.

But we also did a genetic study that found that there is a basket of personality-related non-cognitive abilities that help people succeed in school – being conscientious and open to new experiences, for example. Anything that makes you more likely to take the next step in your education, as it is reflected in your biology, a GWAS will pick it up. It is important to note that people with these genes do not have “good” genes. They have genetic variants which happen to correlate with the pursuit of the school as it is currently constructed.

Are we going to rush to read our children’s genomes to find out their polygenic scores in the future?
People’s imaginations leap into this world of individualized testing and tailored interventions. I don’t think this knowledge is better used as a diagnostic tool on an individual person. There is always a risk that people will receive incorrect or incomplete information. I want to use genetics to better see what is happening in our environments and our social structures.

How should this knowledge be applied, then?
One of the most useful applications is to improve the basic research we conduct to design our broader policies and interventions for all. There are a lot of policy initiatives, and more are coming up all the time. But their research base is limited because it assumes that children only receive environments from their parents, and nothing genetic.

Consider, for example, policies aimed at closing the infamous “word gap”, which is the estimated 30 million word difference between what poor children versus children in high income families hear before they turn three. . The jury is still out on whether “missing word” interventions will be effective, but a glaring problem is that the same vocabulary results that are allegedly the results of exposure to more speech could also be the result of genetics. Parents and children share genes and the same genes that are associated with adult education and income are also associated with early speech and reading acquisition in their children. Before spending millions on interventions designed to change parenting behavior in the hopes of improving children’s outcomes, it would be prudent to at least check this effect.

Ruha Benjamin also suggested the hunt for more data to explain things ends up being a barrier to action on what we already know we need to do to close the academic achievement gap …
I don’t agree that we already know what to do. If you look at meta-analyzes of educational interventions, you see that most of their effect sizes are zero. Most of the things we try in education, even when they are well intentioned and well funded, make no difference in the lives of students. It’s a fiction that we have this army of effective and scalable solutions just waiting behind the scenes. It is very difficult to determine what works for whom and when. The risk of not to talk about genetics is to continue the status quo, where we intervene much less effectively than we could be.

The genetic lottery: why DNA is important for social equality will be published by Princeton University Press on September 21 (£ 25). To support the Guardian and Observer, order your copy at guardianbookshop.com. Delivery charges may apply


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