CHILDREN with strong reading skills are more likely to have higher intelligence levels as young adults, according to a study of identical twins.
Tests carried out on the twins by Scottish university academics suggest that if children have better than average reading skills from age seven, this may positively affect their wider intellectual abilities in late adolescence.
Researchers at Edinburgh University and King's College London tested nearly 2,000 pairs of identical twins. They examined the results of reading and intelligence tests taken by the twins when they were aged seven, nine, 10, 12 and 16.
The scientists used a statistical model to test whether early differences in reading ability between pairs of twins were linked to later differences in their intelligence.
Because twins share all of their genes and grow up in the same home, researchers were able to pinpoint any differences attributable to experiences the twins did not share. These might include a particularly effective teacher, or a group of friends that encouraged reading.
Dr Stuart Ritchie, from Edinburgh University School of Philosophy, Psychology and Language Sciences, said: "Since reading is an ability that can be improved, our findings have implications for reading instruction.
"Early remediation of reading problems might aid not only the growth of literacy, but also more general cognitive abilities that are of critical importance across a person's lifetime."
Mr Ritchie said there was a problem with previous research on the issue because people who read more to their children tended to be of higher intelligence anyway and were also passing on smarter genes to their offspring.
"You cannot get a better control group than an identical twin that is brought up in the same house and in the same family so we can control for any socio-economic factors or genetic factors," he said.
"There has been a move towards evidence-based education and I am pleased to see within schools more experiments about how to improve the teaching of reading, but there is work to be done to ensure that the importance of reading to more general thinking skills is fully understood and acted upon."
Researchers found that early differences in reading were linked to later differences in a range of skills, including verbal intelligence and reasoning. This suggests that tackling problems with reading at an early age could have a range of benefits at a later stage.
The twins tested were part of the Twins Early Development Study (TEDS) an ongoing study led by Professor Robert Plomin at King's College London.
The study is published in Child Development journal. It was funded by the Medical Research Council, the Eunice Kennedy National Institute of Child Health and Human Development, and the European Research Council.
Previous studies have also emphasised the importance of reading to the cognitive development of children.
In 2011 a study by the Organisation for Economic Co-operation and Development which examined the long-term impact of parental support on literacy found children whose parents frequently read with them in their first year of school were still showing the benefits when they were 15.
Discounting social differences, the study found children with early support remained ahead in reading.
The recognition of the importance of reading internationally was reflected last month when the American Academy of Pediatrics announced a new policy to advise all parents about the many benefits of reading aloud in the promotion of literacy and social-emotional skills.
The moves follow research which shows an important part of brain development occurs within the first three years of a child's life, and that reading to children enhances vocabulary and other important communication skills.
Tracy Cooper, early years programme development manager with the Scottish Book Trust, said the research matched previous findings that children who are read to by their parents from a very young age have greatly improved literacy.
She said: "There is a strong movement in Scotland, with backing from the Scottish Government, to encourage all parents to read to their children on a regular basis through our Bookbug programme.
"However, there are still families who are harder to engage because they're facing challenging situations and we need to support all families to help them to see how important reading is for their children's future."