Researchers from the Social Science Genetic Association Consortium set up an experiment that searched two million variable locations known as SNPs in the DNA of 101,069 people for variants that appeared to be linked to educational attainment.
They found only one that was associated with years of education. Two more SNPs were associated with whether a person had finished college.
The researchers then replicated the findings by doing the same sort of analysis on another 25,490 people’s DNA and finding that the same SNPs popped up.
IT has been confirmed: genetic factors may exert a tiny influence on how much schooling a person ends up with. But the main lesson of the research published in May 30 edition of Science by a group of more than 200 researchers, experts say, should be that attributing cultural and socioeconomic traits to genes is a dicey enterprise.
A behavioral geneticist at the National University of Singapore, Richard Ebstein said the study does mark the first time genetic factors have been reproducibly associated with a social trait. “It announces to social scientists that some things they have been studying that make a difference to health and life success do have a base in genetics.”
But even if it does survive further inspection – and many similar links between genes and social characteristics have not?– ?the study accounts for no more than two percent of whatever it is that makes one person continue school while someone in similar circumstances chooses to move on to something else.
Previous studies comparing twins and family members have suggested that not-yet-identified genetic factors can explain 40 per cent of people’s educational attainment; factors such as social groups, economic status and access to education would explain the other 60%.
That percentage attributed to genetics is similar to the heritability of physical and medical characteristics such as weight and risk of heart disease. That makes a hunt for the genetic factors underlying educational attainment an attractive prospect.
Researchers from the Social Science Genetic Association Consortium set up an experiment that searched two million variable locations known as SNPs in the DNA of 101,069 people for variants that appeared to be linked to educational attainment. They found only one that was associated with years of education.
Two more SNPs were associated with whether a person had finished college. The researchers then replicated the findings by doing the same sort of analysis on another 25,490 people’s DNA and finding that the same SNPs popped up.
Considering the apparent effect of all two million SNPs, the analysis can account for only about two per cent of the difference between those with the highest and lowest levels of education.
The single SNP with the strongest effect explains just 0.022 % of the variation in educational attainment in the people sampled. The SNP most strongly associated with finishing college gives people about a 1.8%age point difference in the odds of completing a degree.
It is common for genetic variants to have only weak influences on whether someone will develop a particular trait: Variants associated with height, for instance, exert about a 0.4% influence.
But even scientists used to tiny effects have expressed disappointment at the small contribution of these variants. “It’s not even like a cup half full,” says Robert Plomin, a behavioral geneticist at Kings College London. “It’s a cup that is less than 1 percent full.”
Critics of the study don’t quibble with the way it was done. Their concern – one the authors share?– ?is that there is no gene “for” going to college. The scientists used educational attainment because data on it are available for large numbers of people.
But it is a proxy for something else – perhaps differences in the way peoples’ brains work or in personality traits like perseverance that could help people get through school. That means it is impossible to know what the researchers are really measuring.
The researchers caution that they have not identified specific genes, but merely found variants implicating some regions of the genome in educational attainment. Even if they had pinpointed a particular gene, “it doesn’t tell you the mechanism by which the gene is having a relationship with education,” says study coauthor Daniel Benjamin, an economist at Cornell University.
At best, the study may set an upper limit of effects scientists can expect to find in genetic studies of social traits, says Anna Need, a neuropsychiatric geneticist at Imperial College London.
If a study of so many people can find only marginal genetic associations, smaller studies claiming to have uncovered genes strongly linked to political views or other social values are probably nonsense, she says. She fears that people will interpret the study to mean that genes determine education levels.
It is a fear shared by Duke University geneticist David Goldstein. “This tiny, tiny, tiny signal is completely pointless and will be misinterpreted,” he says. “Now we’re beating the poor methodology to a point that it will confess to pretty darn near anything.”
The variants identified in the study may be false confessions, he says. They barely clear a statistical hurdle at which one in every 20 SNPs seemingly associated with a trait will actually be due to coincidence. “This is literally right on the border,” Goldstein says, and “has a real good chance of being wrong.”
Also, researchers had identified genetic markers that may influence whether a person finishes high school and goes on to college, according to a national longitudinal study of thousands of young Americans.
The study is in the July 2012 issue of Developmental Psychology, a publication of the American Psychological Association.
The study’s lead author, Dr. Kevin Beaver, a professor at the College of Criminology and Criminal Justice at Florida State University said: “Being able to show that specific genes are related in any way to academic achievement is a big step forward in understanding the developmental pathways among young people.”
The three genes identified in the study – DAT1, DRD2 and DRD4 – have been linked to behaviors such as attention regulation, motivation, violence, cognitive skills and intelligence, according to the study.
Previous research has explored the genetic underpinnings of intelligence but virtually none has examined genes that potentially contribute to educational attainment in community samples, said Beaver.
He and his colleagues analysed data from the National Longitudinal Study of Adolescent Health, also known as Add Health. Add Health is a four-wave study of a nationally representative sample of American youths who were enrolled in middle or high school in 1994 and 1995.
The study continued until 2008, when most of the respondents were between the ages of 24 and 32. The participants completed surveys, provided DNA samples and were interviewed, along with their parents. The sample used for this analysis consisted of 1,674 respondents.
The genes identified in this research are known as dopamine transporter and receptor genes. Every person has the genes DAT1, DRD2 and DRD4, but what is of interest are molecular differences within the genes, known as alleles, according to Beaver.
Subjects who possessed certain alleles within these genes achieved the highest levels of education, according to the findings.
Dopamine transporter genes assist in the production of proteins that regulate levels of the neurotransmitter dopamine in the brain, while dopamine receptor genes are involved in neurotransmission.
Previous research has shown that dopamine levels play a role in regulating impulsive behaviour, attention and intelligence.
The presence of the alleles alone did not guarantee higher levels of education, the study found. Having a lower IQ was more strongly associated with lower levels of education.
Also, living in poverty and essentially “running with a bad crowd” resulted in lower levels of education despite the genetic effects.
Even though the genetic variants were found to be associated with educational levels, having a specific allele does not determine whether someone will graduate from high school or earn a college degree, according to Beaver.
Rather, these genes work in a probabilistic way, with the presence of certain alleles simply increasing or decreasing the likelihood of educational outcomes, he said.
“No one gene is going to say, ‘Sally will graduate from high school’ or ‘Johnny will earn a college degree,’” he said. “These genetic effects operate indirectly, through memory, violent tendencies and impulsivity, which are all known predictors of how well a kid will succeed in school.
If we can keep moving forward and identify more genetic markers for educational achievement, we can begin to truly understand how genetics play a role in how we live and succeed in life.”
{Agencies}
