Like pit bull dogs, the psychopath may have a genetic predisposition to lie, kill, cheat, steal, torture, manipulate, and generally inflict great suffering on other humans without feeling any remorse.
It is possible that a genetic marker may be detectable--perhaps in the mitochondria DNA.
The most comprehensive study in human genetics is the National Geographic Human Genome Project. I'm not optimistic that reporting of a "psychopathic gene" would be made by National Geographic as that corporation, a subsidiary of NewsCorp, is complicit in the cover-up of 9/11 with its documentaries on Islamic terrorism and parroting the lies about how the Twin Towers were demolished (NG says 'collapsed').
The article doesn't talk about genetic predisposition and genetic markers--that's a subject that I've enjoyed exploring with a fellow medical professional as we contemplate how such evil as 9/11 would be perpetrated by such a large group of conspirators with apparent lack of remorse.
Think about pit bulls and other animals which are raised for their aggressive behaviors. The same 'evil gene' is likely in humans--perhaps a Neanderthal trait?