It was less than 20 years ago that the National Institutes of Health abruptly withdrew funds for a conference on genetics and crime after outraged complaints that the idea smacked of eugenics. The president of the Association of Black Psychologists at the time declared that such research was in itself “a blatant form of stereotyping and racism.”
The tainted history of using biology to explain criminal behavior has pushed criminologists to reject or ignore genetics and concentrate on social causes: miserable poverty, corrosive addictions, guns. Now that the human genome has been sequenced, and scientists are studying the genetics of areas as varied as alcoholism and party affiliation, criminologists are cautiously returning to the subject. A small cadre of experts is exploring how genes might heighten the risk of committing a crime and whether such a trait can be inherited.
The turnabout will be evident on Monday at the annual National Institute of Justice conference in Arlington, Va. On the opening day criminologists from around the country can attend a panel on creating databases for information about DNA and “new genetic markers” that forensic scientists are discovering.
“Throughout the past 30 or 40 years most criminologists couldn’t say the word ‘genetics’ without spitting,” Terrie E. Moffitt, a behavioral scientist at Duke University, said. “Today the most compelling modern theories of crime and violence weave social and biological themes together.”
Researchers estimate that at least 100 studies have shown that genes play a role in crimes. “Very good methodological advances have meant that a wide range of genetic work is being done,” said John H. Laub, the director of the justice institute, who won the Stockholm Prize in Criminology last week. He and others take pains to emphasize, however, that genes are ruled by the environment, which can either mute or aggravate violent impulses. Many people with the same genetic tendency for aggressiveness will never throw a punch, while others without it could be career criminals.
The subject still raises thorny ethical and policy questions. Should a genetic predisposition influence sentencing? Could genetic tests be used to tailor rehabilitation programs to individual criminals? Should adults or children with a biological marker for violence be identified?
Everyone in the field agrees there is no “crime gene.” What most researchers are looking for are inherited traits that are linked to aggression and antisocial behaviors, which may in turn lead to violent crime. Don’t expect anyone to discover how someone’s DNA might identify the next Bernard L. Madoff.
And that is precisely the problem, said Troy Duster, a professor of sociology and bioethics at New York University, who argues that studies examine not the remorseless and rapacious behavior of the rich and powerful, but the behavior of disadvantaged minorities. “Every era believes that the technology and the methodology have improved,” he said, “but the science itself is problematic.”
One gene that has been linked to violence regulates the production of the monoamine oxidase A enzyme, which controls the amount of serotonin in the brain. People with a version of the gene that produces less of the enzyme tend to be significantly more impulsive and aggressive, but, as Ms. Moffitt and her colleague (and husband) Avshalom Caspi discovered, the effect of the gene is triggered by stressful experiences.
Steven Pinker, a professor of psychology at Harvard whose forthcoming book, “The Better Angels of Our Nature,” argues that humans have become less violent over the millenniums, suggests that the way to think about genetics and crime is to start with human nature and then look at what causes the switch for a particular trait to be flipped on or off.
“It is not a claim about how John and Bill differ, but about how every male is the same,” he said. Understanding the genetics of violence can “tell you what aspect of the environment you should look at.”
He mentioned one of the biggest risk factors leading to crime: remaining single instead of getting married, a link uncovered by Mr. Laub and Robert J. Sampson, a Harvard sociologist who was a co-winner of the Stockholm Prize. Marriage may serve as a switch that directs male energies toward investing in a family rather than competing with other males, Mr. Pinker said.
Kevin Beaver, an associate professor at Florida State University’s College of Criminology and Criminal Justice, said genetics may account for, say, half of a person’s aggressive behavior, but that 50 percent comprises hundreds or thousands of genes that express themselves differently depending on the environment.
He has tried to measure which circumstances — having delinquent friends, living in a disadvantaged neighborhood — influence whether a predisposition to violence surfaces. After studying twins and siblings, he came up with an astonishing result: In boys not exposed to the risk factors, genetics played no role in any of their violent behavior. The positive environment had prevented the genetic switches — to use Mr. Pinker’s word — that affect aggression from being turned on. In boys with eight or more risk factors, however, genes explained 80 percent of their violence. Their switches had been flipped.
A rash of new research has focused on self-control as well as callousness and a lack of empathy, traits regularly implicated in the decision to commit a crime. Like other personality traits, these are believed to have environmental and genetic components, although the degree of heritability is debated.
In findings from a long-term study of 1,000 babies born in 1972 in a New Zealand town, Ms. Moffitt and her colleagues recently reported that the less self-control a child displayed at 3 years of age, the more likely he or she was to commit a crime more than 30 years later. Forty-three percent of the children who scored in the lowest fifth on self-control were later convicted of a crime, she said, versus 13 percent of those who scored in the highest fifth.
But a predisposition is not destiny. “Knowing something is inherited does not IN ANY WAY tell us anything about whether changing the environment will improve it,” Ms. Moffitt wrote in an e-mail. “For example, self-control is a lot like height, it varies widely in the human population, and it is highly heritable, but if an effective intervention such as better nutrition is applied to the whole population, then everyone gets taller than the last generation.”
Criminologists and sociologists have been much more skittish about genetic causes of crime than psychologists. In 2008 a survey conducted by John Paul Wright, who heads graduate programs at the University of Cincinnati’s School of Criminal Justice, discovered that “not a single study on the biology-crime link has been published in dissertation form in the last 20 years” from a criminal justice Ph.D. program, aside from two dissertations he had personally overseen (one of which was Mr. Beaver’s). He also noted that the top four journals in the field had scarcely published any biological research in the past two decades.
Mr. Wright said he now thinks “in criminology the tide is turning, especially among younger scholars.”
But recent work has tended to air outside the main criminology forums. Mr. Beaver, for example, published a paper in Biological Psychiatry in February that concluded that adoptees whose biological parents had broken the law “were significantly more likely to be arrested, sentenced to probation, incarcerated, and arrested multiple times when compared with adoptees whose biological parents had not been arrested.”
At the American Association for the Advancement of Science’s meeting in February, Adrian Raine, chairman of the criminology department at the University of Pennsylvania and a pioneer in the field, presented a paper showing how variations in the parts of a toddler’s brain that regulate emotions — believed to be a product of genes and environment — turned out to be a good predictor of criminal behavior later in life.
Mr. Sampson, who planned to attend the opening day of the justice institute conference, said that “sociology has nothing to fear from genetic research,” but he maintained that the most interesting questions about crime, like why some communities have a higher crime rate than others, are not traceable at all to genetics. “The more sophisticated the genetic research, the more it will show the importance of social context,” he said.
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