Havard University has issued a press release where Christopher F. Chabris, author of a yet unpublished paper on the matter, ponders the elusiveness of genes that could define intelligence.
Twin studies have suggested that there is at least some truth to an association of intelligence (measured by IQ) with inherited genes, however now it seems clear that no individual gene is likely responsible of any notable influence on expressed intelligence.
Chabris ponders that the genetic influence is probably the work of many genes acting collectively and not any single one of them, and also of the interactions of genes and environment.
What our results show is that the way researchers have been looking for genes that may be related to intelligence — the candidate gene method — is fairly likely to result in false positives, so other methods should be used.
Update (Oct 18): the paper is available here (PDF).