The study analyses data from the Children of the 90s project, which is tracking the lives of more than 10,000 young people born in the Bristol area in the early 1990s. The data includes a psychological measure of their mothers’ expectations about how much their own actions influence their life outcomes, collected during the first trimester of pregnancy.

This psychological measure – known as ‘locus of control’ – strongly predicts how well the children performed academically in high-stakes exams at the age of 16.

The locus of control measure is designed to capture individuals’ beliefs about whether the outcomes of their actions are contingent on what they do (‘internal control orientation’) or on events outside their personal control (‘external control orientation’).

"Previous studies have shown that compared with people who have a strongly external locus of control, people who have a strongly internal locus of control tend to invest more in their education. They also tend to live a healthier lifestyle, as well as search for a job much more intensively when unemployed. Our study provides new evidence that they also tend to make better parents," one of the CEP research team, Warn Lekfuangfu, said.

"Holding other things constant – including family background, mothers’ education and children’s own locus of control – we find that children whose mothers ranked in the top 25 per cent of the internal locus of control scale tend to obtain total GCSE scores around 17 per cent higher than children whose mothers ranked in the bottom 25 per cent," said Dr Francesca Cornaglia, an economist from Queen Mary University.

Professor Nattavudh Powdthavee, a senior author of the study, says that part of the observed relationship could be explained by the differences in attitudes towards parenting between mothers who have a strongly internal locus of control and mothers who have a strongly external locus of control: "Mothers who have a higher perceived sense of control over their life early on tend to believe in a more hands-on approach to parenting. This is simply because they strongly believe that their actions will make a difference in their child’s life. Consequently, they tend to engage their children in more cognitively stimulating activities such as reading and singing, compared with an average mother. This seems to give their children a head start in terms of cognitive development compared with other children."

"One of the longstanding debates in scientific research is what matters more – Nature or Nurture? While our study does not offer a definitive answer to this important question, it suggests that just parents having the belief that Nurture matters could potentially make a significant difference to their children’s lives," said the fourth member of the CEP research team, Nele Warrinnier.