I do not agree with Egan on the matter of Amanda Knox, but I could not agree with him more on the matter of Anders Behring Breivik:

On Tuesday, after the site posted the story of the lawyer’s description of Breivik as “insane,” the first comment to follow was this: “I really feel for the guy. He loves his country so much that to see his own culture eroded away by multicultures that the govt is letting in, drove him to this heinous act.”
There were many, many more, of a similar vein. “You gotta like the guy,” another person wrote. “He speaks the truth” and has the mettle “to prove it.”

For an establishment variant of this larger “truth” behind the crime, there was the durable Pat Buchanan, writing on American Conservative’s web site. “As for a climactic conflict between a once-Christian West and an Islamic world that is growing in number and advancing inexorably into Europe for the third time in 14 centuries, on this one Breivik may be right.”

In other words: the madman was onto something with his manifesto.

For all of these reasons, Breivik cannot be dismissed as a lone crackpot whose xenophobia got the most of him. To call him insane and let it go at that is too easy, for him and for the rest of us. His hatred — of Muslims, immigrants and, most of all, fellow Norwegians elected to lead their country — is a familiar virus transplanted to a peaceful country.

In Nature via Nurture: Genes, Experience, & What Makes Us Human, Matt Ridley, the former science editor for The Economist, argues that something like domestic violence against women is not simply a matter of upbringing (the climate of the family or society), but a combination of genetic factors and social factors. In short, it's sociobiological. You can have the genetic propensity for violent behavior, but without a violent climate in the family or society, this tendency is likely to remain just that: a tendency. What I'm trying to get at is that Breivik might have lived a normal life and never expressed his biological disorders (and we all, I think, have disorders of some kind—which is why the social condition is so important), but he was exposed to a social climate that exacerbated/activated these mental/biological factors. This, I think, is what Egan points at in his reading of Olso's Oklahoma.