James Holmes and Adam Lanza: Their DNA May Hold Clues On What Makes a Mass Shooter


Can DNA explain why Adam Lanza and James Holmes both went on shooting rampages?

Some geneticists at the University of Connecticut think so. Backed by a public mandate to look at mental health in the wake of 2012’s rampant shootings, the researchers hope to discover whether there was something unusual about Sandy Hook Elementary School rampage killer Adam Lanza’s DNA. Lanza, who killed 20 children and six staff in an assault on the school, will have his genetic material screened to determine whether aberrant genetic factors such as DNA duplications or deletions or random mutations could have affected his behavior.

Are these efforts going to help prevent the next Newtown or Aurora? No way to tell for sure, but unlikely.

Modern geneticists interpret their results within a near-infinite spectrum of variables including not only DNA analysis but environmental influences. Most recognize there is likely no "smoking gun" genetic answer which can adequately explain outlier cases of extreme violence.

Skeptics allege that as many as hundreds, if not more, of genes are linked to bizarre violent behavior, along with environment and psychological influences, all of which link together in extremely complicated – and highly unpredictable – ways. “It is almost inconceivable that there is a common genetic factor… I think it says more about us that… we wish there was an explanation,” said Harvard neurologist Dr. Robert Green.

Overall, it seems very unlikely that the University of Connecticut team will be able to provide data useable in law enforcement and prevention efforts. Not only would Adam Lanza’s genetic profile be uniquely tied to his own actions and interlinked with a highly specific number of environmental factors, genetic screening on other shooters is near-certain to be carried out after their crimes. There is little preventative value there. Genetics have mixed predictive value on antisocial behavior, particularly in the case of extreme outlier behavior with no clearly biological cause.

Some respondents worried that efforts to prematurely profile other potential shooters using genetics could backfire, causing them increased psychological stress and hurting treatment efficacy. According to Dr. Steven Hyman, director of the Broad Institute’s StanleyCenter for Psychiatric Research, “the idea of screening with a view of preventing those kinds of incidents is totally unthinkable. You would fail. You would stigmatize.”

J.H. Skene, a Duke University neurobiologist, said research into the genetics of a shooter is a “certainly a good idea,” but cautioned that even if significant genetic linkage was found, that alone was not sufficient evidence that a person was capable or likely to commit a violent action.

The focus on mental health, if undertaken genuinely, is certainly a good thing. But it could also overlook other environmental factors which influence behavior, such as the prevalence of firearms in private possession. There are 88.2 guns in private possession for every 100 Americans, and evidence suggests that access to firearms can catalyze violent actions. A 2003 study in the Annals of Emergency Medicine “estimated that 41% of gun-related homicides and 94% of gun-related suicides would not have occurred had guns not been present. The Harvard School of Public Health echoes such grim findings.” These factors have to be taken seriously in any effective psychological profile.

So while there may have been something genetically different about Adam Lanza, James Holmes, William Spengler and the other mass-murderers who hit this year, those results are unlikely to have any major impact on either identification of potential shooters or prevention of future incidents, at least in the near future.