Genes that can be pinned to intelligence are proving frustratingly
hard to find, the British weekly New Scientist reports in next
Researchers led by Robert Plomin of the Institute of Psychiatry in
London obtained intelligence scores for 7,000 seven-year-olds based on
verbal and non-verbal reasoning tests.
They also took DNA samples from the children in the hope of
identifying genetic differences between the high and low scorers.
The huge trawl identified 37 variants in six genes that appear to
play some role in differences in intelligence.
But the individual effects of these genes was barely detectable.
Together they account for just one percent of the variation in
intelligence between individuals.
Upbringing plays a role
Previous research, based on twins and adopted children, suggests
that about half of the variation of intelligence is due to upbringing
and social factors, and the rest is inherited.
Even though the genetic link to intelligence is proving so elusive,
that doesn't mean that this 50-50 proportion should be reviewed, New
It simply implies that a complex trait like intelligence clearly
results from the cumulative effect of a wide combination of genes,
rather than individual ones, it says.
"Intelligence is a function of the way the brain is put together,
and at least half of our genome contributes in some way or another to
brain function, which means that in order to build a human brain, you
need thousands of genes to work together," New York University
psychologist Gary Marcus told the publication. – (Sapa/AFP)
7 ways for young children to be smart