Can criminals blame their genes? Is IQ or sexuality genetically determined? Annabel Gillings says that recent advances in genetics have increased our understanding of the biological basis of behaviour, but environmental influence remains vital tooby Annabel Gillings / October 20, 1996 / Leave a comment
In 1994, Stephen Mobley, confessor to a cold-blooded murder, was the first to offer genetic evidence in mitigation in a court of law in Atlanta, Georgia. Despite a privileged homelife, Mobley’s family tree showed four generations of violence; his attorneys argued that his crime could be attributed to his genetic make-up. The court rejected the claim. But the introduction of genetic defence into the courtroom was an important step for both law and genetics.
The defence was based upon the discovery of a “criminal gene” in a Dutch family. Although the family was large and living across different regions of the Netherlands, they shared the same problem: for 35 years, many of the men had been aggressive and prone to violent impulsive acts such as rape and arson. Women in the family approached Han Brunner of the Institute of Genetics in Nijmegen, anxious to find out how to stop the trait, which was mysteriously passed on by women and expressed only in men.
The family’s violent behaviour followed a pattern that Brunner was able to trace to a single gene. He found that the pattern was being genetically transmitted on the X chromosome, which is not duplicated in men and therefore cannot be “over-ridden” by a partner chromosome as it is in women.
The location of this “criminal gene” caused a great commotion. Suddenly, it seemed that not only physical traits such as eye and hair colour could be passed in the genes from parent to child, but also characteristics so intangible as a tendency for arson, religious behaviour or linguistic aptitude.
The last year has seen the discovery of the “gay gene,” “the criminal gene” and even the gene “that stops you from being boring.” In April this year, Chris Brand, a psychologist at the University of Edinburgh, caused outrage by suggesting that single mothers should be encouraged to “sire” their children by more intelligent, and hence more genetically desirable men. The American science writer Chandler Burr, who is both gay and a devout believer in a “gay gene,” even suggested that once the particular gene is “verified,” homosexuality might be “treated” with antibiotics. And in August, a single gene which conferred maternal behaviour upon mother mice was reported in Science. Female mice lacking the gene shunned their babies and left them for dead.
Nature and nurture
Most experts agree that the nature versus nurture debate is pass?.…