Is Neuroscience Threatening Liberalism?

In the Economist, what do discoveries in neuroscience imply about free will?

IN THE late 1990s a previously blameless American began collecting child pornography and propositioning children. On the day before he was due to be sentenced to prison for his crimes, he had his brain scanned. He had a tumour. When it had been removed, his paedophilic tendencies went away. When it started growing back, they returned. When the regrowth was removed, they vanished again. Who then was the child abuser?

His case dramatically illustrates the challenge that modern neuroscience is beginning to pose to the idea of free will. The instinct of the reasonable observer is that organic changes of this sort somehow absolve the sufferer of the responsibility that would accrue to a child abuser whose paedophilia was congenital. But why? The chances are that the latter tendency is just as traceable to brain mechanics as the former; it is merely that no one has yet looked. Scientists have looked at anger and violence, though, and discovered genetic variations, expressed as concentrations of a particular messenger molecule in the brain, that are both congenital and predisposing to a violent temper. Where is free will in this case?