Inherited wealth: uncovering the genes that set you up for life
Research has shown that many social and economic outcomes are moderately heritable, suggesting they are linked to a certain collection of genes. The EU-funded EdGe project sought to expand our understanding of this phenomenon through large-scale genome-wide association studies. The majority of project coordinator Philipp Koellinger’s research in the past 5 years has focussed on the effects of genes on educational attainment – the number of years a person spends in school or college. He caused a splash when, in 2013, he published a genome-wide association study in ‘Science’ showing that single nucleotide polymorphisms (SNPs) on 3 genes correlated with educational attainment. “The effect was extremely small, and only seen if the sample included more than 100 000 people,” explains Koellinger. This, he says, was the reason that previous studies on much smaller groups had failed to detect a conclusive link.
Missing heritability
That paper also opened the door to the EdGe project, as Koellinger and his team at Vrije Universiteit Amsterdam sought to uncover more genes linked to educational attainment. “We know socio-economic status has a heritability of 40-50 %, and researchers could only identify a tiny part of that previously,” he adds. “My project was trying to uncover that missing heritability.” Koellinger tackled this by dramatically increasing the sample size of his genome-wide association studies. A 2016 paper published in ‘Nature’ examined the genetics of 300 000 people to uncover 74 SNPs that influence educational attainment. “With the results you can generate a genetic index, which weighs genes in a hold-out sample with their estimated effect sizes,” notes Koellinger. “We could capture about 2 % of educational attainment with such an index in the 2013 study, and 5-7 % in the 2016 study. There was a substantial increase.” Koellinger’s next step was to draw genetic information from more than 1 million people, the largest genome-wide association study ever conducted at that time. “We went from 74 to more than 1 000 SNPs linked to educational attainment. Our genetic index now captures 10-14 % of what affects years of schooling. That’s quite substantial, on par with the income of parents,” says Koellinger. He and his team were able to expand their search this wide by using already existing data that had been collected for other genetic studies in the past, all of which had asked for the subject’s level of educational attainment as a routine question before sequencing their genes.
Career focus
The work was supported by the European Research Council. “This allowed me to focus my career on genetics – you cannot be at the forefront of this fast-moving field unless you’re working on it full-time,” notes Koellinger. He adds that the support also allowed him to hire “a number of extremely talented and hardworking PhD students and postdoctorates who played crucial roles in the papers that came out of that research.” The genes the EdGe project identified are not unique to educational attainment, and are linked to hundreds of other outcomes, such as infant skull size, childhood intelligence, income, occupational status, mental health, cardiovascular health and dementia, and even predict longevity to some extent. These results, explains Koellinger, invite much discussion about potential policy implications: “It’s pure luck who our parents are, and what genes they pass down, but that luck has huge implications for how well we do in life. I think the results we have very strongly argue in favour of designing society in a way that compensates for the disadvantages people have and that are not their fault.”
Keywords
EdGe, educational attainment, genetics, genome-wide association, single nucleotide polymorphisms