"As crazy as it sounds, there may be a closer link than than most people would think between the extreme-altruistic personality and sociopathic personality. Would it shock you to know that two people, one with the traits of extreme-altruism (X-altruism) and the other the traits of a sociopath, could be related? Even siblings? And that their personality traits are very similar, with only a few features to distinguish them? Research by Watson, Clark, and Chmielewki from the University of Iowa, “Structures of Personality and Their Relevance to Psychopathology” [pdf], present a convincing argument in which they support the growing push for a trait dimensional scheme in the new DSM-V to replace the current categorical system." - Steven Perez from Bookmarklet