Jesse Bering runs through some of the crazier case studies on nymphomania and concludes:

If a "good" person's brain can be rendered morally disabled by an invasive tumor or an epileptic fuse-shortage, subsequently causing them to do very bad deeds, then isn't it rather hypocritical to assume that a "bad" person without brain injurywhose brain is anatomically organized by epigenetics (the complex interplay between genes and experiences)has any more free will than the neuroclinical case? After all, perhaps it's just a matter of timing: The "good" are born with brains that can "go bad," whereas the "bad" are hogtied by a morally disabled neural architecture from the very start. And although it may be less common, if a "bad" person behaves in an upstanding manner, could that be the result of fortuitous brain damage or epilepsy, too?

It's all brain-based in the end, including the parameters by which one can contemplate and, especially, execute their free will. Perhaps we're only as free as our genes are pliable in the slosh of our developmental milieus.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.