“The right loves genetic explanations for poverty or mental illness,” claims Oliver James. The problem, he says, is that a decade of scientific research does not support their views, and that genes may never explain most psychiatric disorders and mental illnesses: 

When the map of the human genome was presented to the world in 2001, psychiatrists had high hopes for it. Itemising all our genes would surely provide molecular evidence that the main cause of mental illness was genetic – something psychiatrists had long believed. Drug companies were wetting their lips at the prospect of massive profits from unique potions for every idiosyncrasy.

But a decade later, unnoticed by the media, the human genome project has not delivered what the psychiatrists hoped: we now know that genes play little part in why one sibling, social class or ethnic group is more likely to suffer mental health problems than another. … Another theory was that genes create vulnerabilities. For example, it was thought that people with a particular gene variant were more likely to become depressed if they were maltreated as children. This also now looks unlikely.

This February’s editorial of the Journal of Child Psychology and Psychiatry was entitled “It’s the environment, stupid!”. The author, Edmund Sonuga-Barke, stated that “serious science is now more than ever focused on the power of the environment … all but the most dogged of genetic determinists have revised their view”.

More here (via Louise Gordon). The article has an odd claim attributed to Venter, about 30,000 genes not being enough. That and more, I think, are clarified in this brisk and entertaining 2007 lecture by Dr. Gregory Forbes on the “genes vs. environment vs. free will” debate.