Deep divide of 'evil genes' Sandy Hook Elementary shooter Adam Lanza, pictured in 2005. Adam Lanza was a loner: highly intelligent with a ghostly pallor; awkward but seemingly pleasant; described by his own brother as a "nerd." On December 14 last year, Lanza, 20, walked into Sandy Hook Elementary School in the affluent town of Newtown, Connecticut, and over the next two hours shot 20 children and six adults dead, before turning the gun on himself. Already that day, he had killed his mother with her shotgun. Why had this young man, as opposed to millions of other "geeky" outsiders, murdered 27 innocents? The media talked about Lanza's mother's gun collection; the fact he had no Facebook page and no photo of him appeared in his high-school yearbook, only the words "camera-shy." But at the same time, scientists at the University of Connecticut were embarking on a different line of inquiry. The genetics department was analysing Lanza's DNA. Anders Breivik. The university refused to give any details about these investigations - possibly of cells from Lanza's brain, but equally likely from cells taken from his hair or the gun he used - or what they hoped they could reveal from the analysis. But the news shone a light on an area of behavioural genetics that provokes deeply divergent opinions both within the scientific community and in wider society. Is it possible that there is a gene that makes some people "evil"? Could future murderers be spotted before they have committed a crime? And should they be punished if they are simply prisoners of their own biology? Some scientists rejected the announcement, saying it was "almost inconceivable" there was a common genetic factor among mass murderers. But others applaud the initiative. "Only by studying individuals [like Lanza] as thoroughly as possible will we some day be able to reduce the frequency of these sad episodes," says Dr Art Beaudet, chairman of the Department of Molecular and Human Genetics at Baylor College of Medicine in Houston, Texas. Martin Bryant. This is thought to be the first time that scientists have analysed the genetic blueprint of a "spree killer," but it's far from the first attempt to examine a murderer's biology. Over the past decade, Dr Kent Kiehl, a neuroscientist at the University of New Mexico, has visited eight high-security prisons in two US states with a mobile MRI unit, scanning the brains of criminals to see if those defined as psychopaths have different brain structures from "someone who commits a robbery out of poverty," as Kiehl puts it. Kiehl's and others' research has found that psychopaths' brains tend to have very low levels of density in the paralimbic system, the area of the brain associated with the processing of emotion, something that may be genetically determined. The result is that psychopaths tend to have impulsive personalities and show little evidence of feeling guilt, remorse or empathy. In contrast, "spree killers" tend to be extremely depressed, to the point of suffering from a delusional psychosis accompanied by voices or hallucinations, or - as in Lanza's case - to be young people with physiologically immature brains, who in their state of ultra-sensitivity decide to exact "revenge" on the world for perceived injustices. Recent years have seen huge advancements in DNA research, with researchers now able to identify specific genes that are linked to anti-social behaviour, in particular the MAO-A gene (nicknamed "the warrior gene"), which appears to be hereditary. Irving Gottesman, a psychologist at the University of Virginia who has worked on the Danish twin study, believes the results show that "criminals are not born, but the odds at the moment of birth of becoming one are not even." But so controversial are the links between biology and violence that only the bravest scientists have dared tackle it. In the United States, projects set up to investigate the issue have been shelved after public uproar. Scientists are haunted by the ghosts of the pseudoscientific eugenics movement, which held that mankind could be improved by breeding out the bad. Peaking in the early 20th century, its influence led to the sterilisation of mental patients and prisoners and, by extension, to Hitler's "final solution" of eliminating the "Untermenschen." Today, opponents of such research worry that because minority groups tend to commit most crimes, we will blame their colour, which is genetically determined, rather than their low socio-economic status. Others fear that if criminal urges are shown to have biological or genetic origins, then crime will no longer be associated with parents, society, education - or anything else that has the potential to be improved. "Looking at a criminal's environment is hard," Taylor says. If you say Lanza was a loner, he watched too much television and Hollywood culture is far too violent, then it spreads the responsibility, it makes us all feel uneasy. It's far easier to say it's all about the genes. Lanza spent hours on the internet, a fact likely to make any parent of a teenager uncomfortable. His parents had also divorced bitterly - tough news for similar couples to swallow. Will the concept of evil become extinct, replaced by a notion of a functioning or malfunctioning brain? Would we continue to reward virtue? Would we continue to praise heroes, or would we simply acknowledge that they had a well-developed amygdala? Such questions have already made the new fields of neurolaw and neuroethics hot topics. Universities, law schools and, increasingly, the judicial system are all reviewing cases where it seems "the brain" rather than "the person" might be culpable. In the US, several killers have been sentenced for manslaughter rather than murder after DNA evidence was produced to show the perpetrator had unusually high levels of MAO-A. Naturally, such cases are greeted with horror by victims' families. The flip side to such developments is an Orwellian world where any potential criminal is locked up, and the key thrown away. Many fear that carriers of "criminal" genes could be identified even in the womb, raising a question of what to do with the embryos. Essi Vidling, professor of developmental psychopathology at University College London, who has carried out extensive research into psychopathy in children, describes the research into Lanza's genes as "a complete bloody waste of time." Yet she agrees juries love nothing more than brain scans. "They are seriously fascinated by these images and studies have shown they are much more likely to believe an argument when it's backed up by pictures of the brain," she says. But everyone I know in the field who does responsible research doesn't think these data are ready to go into a courtroom. Even scientists who have proved the unusual brain structures of psychopaths believe it is still impossible to dismiss environmental factors. Nearly all psychopaths suffered physical and emotional abuse as children. Scientists also point out that brain structures can be altered by environmental factors, meaning no one is destined for a life of crime, just as someone with large hips is not doomed to heart disease if they eat healthily and exercise. With so many other factors to consider, what is the point in investigating criminals' brain chemistry? According to Dr Nigel Blackwood, of the Institute of Psychiatry at King's College London, it's to tailor appropriate therapy for those who commit crimes in "hot blood," as opposed to the differently wired "cold-blooded" criminals. "For most conduct-disorder children parent-training programs work well, but they're less successful with children with callous and unemotional traits," he says. We need to adapt treatments for this group. Could things have been different for the Lanza family if their youngest son's brain had been scanned at an early age? It's all conjecture. As Kent Kiehl says: "The only thing we can be sure of is that if Lanza's mother had locked away her guns, this tragedy might have been avoided." The Sunday Telegraph, London