Their analysis showed that bad behaviour without psychopathy has relatively little genetic component less than a third.
But it does mean that far from being an aberrant behaviour, psychopathy may be disturbingly normal.
Psychopaths scored much less around 40% and those in the middle of the psychopathy scale scored midway between the two.
Further research will be needed to see how the risk and social-contract modules that govern psychopathy are actually controlled.
"There is no doubt in my mind that he passes the threshold for a diagnosis of psychopathy, " he said.
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To find out, they recruited 67 prisoners and tested them for psychopathy.
While extreme, narcissism and psychopathy are examples of toxic emotions that run amok in the workplace especially when emanating from our leaders.
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All got high scores on the Psychopathy Checklist, the "gold standard" in the field, which assesses traits like lack of remorse, callousness and grandiosity.
However, I would not accept for a minute a verdict of psychopathy based on a selective combination of characteristics of half a dozen different individuals.
While environmental factors play a part, psychopathy is rooted in biology.
On an intellectual level, it asks about the origins of psychopathy.
Claims that criminals can be identified by imaging their brains, or that there could be a gene for psychopathy are "wide of the mark", it says.
They then subdivided these children into those with psychopathic traits and those without and asked, in each case, whether an individual's twin showed bad behaviour, psychopathy, or both.
Narcissism shares aspects of psychopathy.
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Researchers tested their hypothesis in the 42 U.S. presidents up to and including George W. Bush using (a) psychopathy trait estimates derived from personality data completed by historical experts on each president, (b) independent historical surveys of presidential leadership, and (c) largely or entirely objective indicators of presidential performance.
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