Children's ability to score better grades may be encoded in their DNA, say scientists who found that around two-thirds of individual differences in academic achievement can be explained by comparing genes.
For many years, research has linked educational achievement to life trajectories, such as occupational status, health or happiness.
However, researchers from the University of Texas in the US and King's College London in the UK showed that genes have a substantial influence on academic success, from the start of elementary school to the last day of high school.
The study, published in the journal npj Science of Learning, analysed test scores from primary through the end of compulsory education of more than 6,000 pairs of twins.
Researchers found educational achievement to be highly stable throughout schooling, meaning that most students who started off well in primary school continued to do well until graduation.
Genetic factors explained about 70 per cent of this stability, while the twins shared environment contributed to about 25 per cent, and their nonshared environment, such as different friends or teachers, contributed to the remaining five per cent.
"Around two-thirds of individual differences in school achievement are explained by differences in children's DNA," said Margherita Malanchini, a psychology postdoctoral fellow at the University of Texas.
"But less is known about how these factors contribute to an individual's academic success over time," said Malanchini.
However, this does not mean that an individual was simply born smart, researchers explained. Even after accounting for intelligence, genes still explained about 60 per cent of the continuity of academic achievement.
"Academic achievement is driven by a range of cognitive and noncognitive traits," Malanchini said.
"Previously, studies have linked it to personality, behavioural problems, motivation, health and many other factors that are partly heritable," she said.
However, at times grades did change, such as a drop in grades between primary and secondary school. Those changes can be explained largely by non-shared environmental factors, researchers said.
"Our findings should provide additional motivation to identify children in need of interventions as early as possible, as the problems are likely to remain throughout the school years," said Kaili Rimfeld, a postdoctoral researcher at King's College London.