This probably stems from the recent Horizon documentary entitled good or evil, broadcast on Monday night. The jist of the documentary was that psychopathy could be screened for, using a combination of DNA screening ( looking for the Monoamine oxidase A enzyme, expressed when the MoA gene is switched on), the lack of activity in the hypothalamus region of the brain ( as determined by a PET scan), and a personal history of a severely abusive childhood.
All these traits were exhibited, to a greater or lesser extent, by some of the more infamous serial killers of our time apparently. It is one thing to posit a hypothesis however, quite another to prove it - and as the programme itself pointed out, one of the main researchers into this area, a world renowned authority, himself had the MoA gene and the MRI brain scan pattern suggestive of being a psychopath. It is also true to say that some of the worlds leading lights have a similar combination.
So one cannot simply screen for the gene and then arbitrarily label individuals positive for MoA as probable psychopaths - It is, as ever, more complicated than that.