Mention of the movement to improve human genetics known as eugenics today evokes myriad horrors, including its association with forced sterilization, American racism, and Nazism.

But over a century after the beginning of the eugenics movement, scientist are carefully dipping back into the controversial research that looks at the influence genes have on certain behavioral characteristicssuch as intelligence, the likelihood of going to university, and even the amount of time a teen spends on social media.

While eugenicsthe term derived from Greek words for good and birthwas once used to justify entrenched inequality and systemic racism, some now argue that understanding the role of genetic predispositions can help achieve equal opportunities for all.

Francis Galton is widely known as the father of the eugenics. A younger cousin of Charles Darwin, Galton was the first to apply a version of Darwins theory of survival of the fittest to humans. In Hereditary Genius, published in 1869, Galton argued that everything from criminality to love of poetry was thought to be in the hereditary nature of humans, says James Tabery, a philosophy of science professor at the University of Utah. And, the theory went, that if society wanted less criminality and more poetry-loving people, then criminals would have to breed less and the people who love poetry breed more.

Of course, Galtons ideas didnt remain confined to academia. In the UK, the government passed the Mental Deficiency Act in 1913, which emphasized one principle; the separation of people with learning disabilities from the rest of the community. Though the act had near unanimous support, one of the MPs who condemned the law, Josiah Wedgwood, said: the spirit at the back of the Bill is not the spirit of charity, not the spirit of the love of mankind. It is a spirit of the horrible Eugenic Society which is setting out to breed up the working class as though they were cattle.

The US went even further. An estimated 60,000 people were sterilized in the US between the 1930s and 1970s. The federal backed procedures largely targeting the disabled, mentally ill, people of color, and the poor, were finally repealed in the 1970s. Eugenics was also used to justify the miscegenation laws that prevented people from different races from marrying, and it fed into anti-immigration rhetoric.

American sterilization efforts apparently inspired Adolf Hitler, and eugenics ideas helped inform Nazi Germanys final solution, where millions of Jewish, disabled, Roma, and LGBT people were murdered.

Following this litany of horrors, the 1940s saw a recoiling from eugenics, and a scientific undermining of the movements basic principles. Leading academics instead highlighted sociocultural explanations for differences and inequality.

This didnt mean that efforts to improve the human race through genetic selection were completely sidelined. The field slowly morphed into a field of science now known as human behavioral geneticsa field of science where researchers explore how genetics influences human behavior.

US behavioral geneticist David Lykken is a notable example. In 1998, Lykken advocated for a so-called parenting license. He argued that couples interested in having children should need to get a license, but those who were unmarried, unemployed, or disabled would be denied. The licensure of parenthood is the only real solution to the problem of sociopathy and crime, Lykken noted in his infamous paper.

In the last decade, however, a new approach to genetic research has been on the rise, one that argues for understanding its role in social mobility as a way to achieve greater equality for all. A recent study published in the journal Psychological Science last week tested the role genetics plays in parent-child association in education attainment.

Researchers found, as in previous studies, that the likelihood of a child going on to higher education is heavily influenced by their parents education. But while previously, this was largely attributed to environmental factorsthe argument being that parents who have been to university can provide more support in the early secondary years and advice when their child is applying for universitythe new study indicates that genetics may also play a role. Until now, Genetics is largely ignored in this dialogue, said Ziada Ayorech, the lead author of a recent study.

Ayorech, from the Institute of Psychiatry, Psychology and Neuroscience at Kings College London, and the other researchers looked at a sample of more than 6,000 families with identical and non-identical twins in the UK. They categorized the families into four groups:

The researchers used two methods to figure out to what extent social mobility is mediated by genetic differences. The first method is the traditional twin study design, in which researchers compare identical and non-identical twin pairs. If identical twin pairs were more similar in social mobility then non-identical twin pairs, then this was the first clue that genetics is important.

The second method used polygenic scores, a new scientific technique at the forefront of genetic analysis. Unlike the first method, which relies on comparisons between twin samples, polygenic scores is a predictive method based directly on DNA. Researchers looked at unrelated individuals, within the four groups, whose DNA they had information on. They looked at the extent to which genetic differencesthose differences in the letters of someones DNAcontribute to differences in social mobility.

With the first method, we found genetics played a substantial role. It explained 50% of differences in whether families were socially mobile or not, Ayorech explains. The second method mirrored the twin results, she adds.

The polygenic scoreswho had the most bits of DNA associated with higher levels of educationdiffered across these four groups. Those families that had the highest level of education had the highest polygenic scores. The lowest score was found in the families where the parents and children did not have higher education.

The researchers were keen to stress that though their results indicate that genetics played an important role in social mobility, genetics doesnt work in isolation from socioeconomic factors. Its always an interaction between the two, Ayorech says. Finding genetic influence on something that is traditionally seen as an environmental measure should highlight the fact that genes and environment are working together, Ayorech says. Even if something is highly genetically drivensuch as heightit doesnt mean genes are the only factor. Diet and their lifestyle also impact height.

The researchers also emphasize how their research could be used to promote social mobility. Ayorech suggests that even in a scenario where equal educational support has been provided for everyone, childrens outcomes will still vary. The students themselves will differ in the extent they take on these opportunities, in their aptitude, and in their appetite for education. Knowing the role genetics plays can lead to more tailored, personalized support to maximize the potential for each child, she argues.

She points towards preventative measures that are currently championed in medicine. People at risk of type two diabetes are put in prevention programs, where they get tailored, personalized support to reduce their risk. She says the same could be done in education. Children are already genetically screened for a whole host of conditions, and researchers could one day look at a genetics risk score that predicts learning disabilities. Rather then waiting until the child comes into school and then struggles, Ayorech says, early intervention can be put in place to provide more tailored support. We are a long way from applying this research effectively, Ayorech acknowledges. Researchers dont yet have the sophisticated tools to genetically screen a large enough sample size of children to do educational intervention.

Still, thats a fairly new idea, Tabery says. For the longest time, if anybody was introducing talk of genetics and intelligence with policy implications, they were doing it in the name of inequality, and these authors are trying to use it towards equality.

There lies the difference between genetics research in the 1930s and now, Tabery says: They are really going out of their way not to fall into the traps of the really reprehensible stuff.

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Mindful of eugenics' dark history, researchers are reexamining the genetics of social mobility - Quartz