Researchers have found that intelligence is mostly in our genes, suggesting that the cleverness we inherit from our parents may be as important as the amount we study.
A team led by University of Edinburgh scientists took blood and saliva samples from around 20,000 people aged 18 to 99 to examine their DNA.
The genes and rare genetic variations of volunteers were compared with their performance in general intelligence tests and in tests of vocabulary, memory and mental-processing speed. The researchers found that 54 percent of the difference in intelligence between people is written in the genes, so the brainpower we are born with may determine our future.
The findings will fuel the ‘nature versus nurture’ debate over what explains differences in intelligence. As well as genes, environmental factors such as parenting, nutrition and exposure to chemicals in the womb are also thought to have a significant effect.
Dr David Hill, from the University of Edinburgh’s centre for cognitive ageing and cognitive epidemiology, said: ‘We used two methods to measure the effect that rare variants had on intelligence. By combining the effect of both rare and common variants, more than 50 percent of the differences in intelligence between people could be traced to their genes.’
Previous studies have suggested that 30 percent of someone’s intelligence is inherited from their parents, compared with a maximum of 15 percent of their personality.
The researchers, whose study is published in the journal Molecular Psychiatry, looked at unrelated people, siblings and couples to show that people who were more similar genetically were also more similar in terms of their level of intelligence.
– Daily Mail