These two 'extreme' parenting styles can turn children into psychopaths.

Extreme parenting can be linked to criminal psychopathy, psychologists warn.

British psychologist Dr Jeremy Dean says the criminal psychopath is not just born — they are also made. He has resurfaced a study that found total parental neglect or rigidly controlling children can be harmful.

Lead study author, Dr Aina Gullhaugen, said adult psychopaths have been damaged in childhood.

“Without exception, these people have been injured in the company of their caregivers,” Dr Gullhaugen said, according to Psyblog.

“And many of the descriptions made it clear that their later ruthlessness was an attempt to address this damage, but in an inappropriate or bad way,” she added.

The Norwegian University of Science and Technology study author said most parenting styles sit “in the middle” between absence of care and a “totally obsessive parent”.

"But it is different for psychopaths," she said.

"More than half of the psychopaths I have studied reported they had been exposed to a parenting style that could be placed on either extreme of these scales.

"Either they lived in a situation where no one cared, where the child is subjected to total control and must be submissive, or the child has been subjected to a neglectful parenting style.”

But Dr Dean says parents cannot be blamed for everything.

"After all, some children have awful upbringings and don’t become criminal psychopaths," he said on Psyblog.

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Report author Dr Gullhaugen says not all reckless behaviour is explained by a bad upbringing, but admits "we do not inherit everything either".

"You do not get a personality disorder for your eighteenth birthday present,” she said.

Writer Scott A Bonn describes psychopathic criminals as "cool, calm, and meticulous".

"Psychopathy is related to a physiological defect that results in the underdevelopment of the part of the brain responsible for impulse control and emotions," Professor Bonn said in Psychology Today.