Researchers search for genes behind intelligence, find almost nothing

Flickr user Charles Strebor

To what degree do genes determine how intelligent we are? It's a question with a lot of social implications, given the potential for people to get lumped into categories based on their inheritance—or for them to make a self-fulfilling prophecy out of it.

But so far, at least, it's a question that science has been unable to answer. When scientists have focused on specific genes involved in the nervous system's growth and function, they've found a few hints of associations, but those haven't held up in large population studies. Large population studies that scanned the entire genome have also come up empty.

Now, we may have a good idea why. A massive and thorough genetic study has looked into the question and, despite all the effort involved, has only come up with three genes, none of which have a very large effect on cognitive abilities.