And, it would make sense that a disproportionate number might work on Wall Street. Certain maladaptive personality traits (a lack of empathy, an increased willingness to take risks) might be considered desirable in some settings (a cautious person overly concerned with the feelings of others might not be the best fit at an investment firm).

Also, there are studies that support the idea that corporate executives have certain personality traits. Researchers at the University of Surrey found that, compared to criminal psychiatric patients, senior business managers were more likely to have one of three personality disorders (histrionic, narcissistic, and obsessive-compulsive). And, in 2010, researchers studied 203 participants in management development programs at seven different companies and found that approximately four percent met the diagnostic criteria for psychopathy. While not studies of the financial services industry specifically, they do support the notion that there may be more psychopaths in the corporate and financial world than in the general population.

Still, though, the estimate that 10 percent of those in the financial services industry are psychopaths is precisely that -- an estimate that is not based on any scientific study. And it ignores an important concept: psychopathy is not an "on/off" proposition -- it exists on a continuum (as shown by the PCL-R scale, which ranges from 0 to 40). There are those whose scores do not reach the top 25 percent of the scale and who would not be diagnosed as psychopaths, but whose manipulative and uncaring actions may cause great suffering to those around them. These are the people who my colleague Ronald Schouten (an associate professor of psychiatry at Harvard Medical School) and I refer to as "almost psychopaths" in our forthcoming book, Almost a Psychopath. Almost psychopaths differ from true psychopaths not in the types, but, rather, in the frequency and intensity of their remorseless and damaging behaviors.

Research studies suggest that as much as 15 percent of the general population (that's about 45 million Americans) can be characterized as almost psychopaths. If Wall Street does, in fact, select for people who display certain characteristics of psychopathy, it is safe to assume that at least 15 percent of people in the financial services industry are almost psychopaths (and, therefore, more prone to acts of fraud, deceit, and self-serving manipulation).

So, yes, Wall Street may have a significant percentage of self-serving, ruthless, and manipulative psychopaths and almost psychopaths. And, yes, this fact might be of considerable importance in assessing the "moral fiber" of an investment bank. Whether this is a new phenomenon, though, is a separate question. And, in the current zeal to castigate Wall Street, let us not lose sight of the fact that about one out of every 100 people is a psychopath and 15 out of every 100 people are almost psychopaths. They are husbands, wives, doctors, lawyers, teachers, and store clerks.

And they are a lot closer to you than Wall Street.