Part of the show The Genetics of Brain and Behaviour
Nish Naya, Facebook asked:
ďWhat makes us more intelligent? Do we know of any specific physical or genetic differences found in individuals who have very high IQs?Ē
Dr John Rogers, Cambridge University - First of all, itís not just genes that affect intelligence. Itís strongly affected by environment as well as by genetics, and the two of them interact. And the stimulating environment in infancy is certainly important in influencing intelligence. But there do appear to be genes that determine intelligence, but searches for specific ones have not yet come up with very much.
In fact only recently, the first such gene was identified and it just has a small effect on IQ. If you have a particular version of this gene, it increases IQ by about 1.3 points which really isnít very much. And this gene is a gene thatís generally in the nucleus to operate on expression of other genes and it seems to affect the size of the brain. So that may be why itís affecting IQ.
Otherwise, we might expect thereíll be other such genes which contribute in a rather general way to brain development or to brain function, and there may again be some variance of them which allow for more effect to development to the circuits which integrates and interpret experience within the brain.
In addition to general intelligence as it were, there will also be genes that contribute to specific learning disabilities and there's been some progress in finding some of those recently, and there are some genes which seem to influence the chance of developing dyslexia and also other psychological conditions such as autism.
There are genes that influence the chances of developing those and those tend to be rather rare variance of genes which affects just a few people, but seem to predispose to those conditions in those people.