These were located on chromosomes 13 and 14, near genes that have functions which may be relevant to the development of sexual orientation.Īlan Sanders, a psychiatrist who studies behavioural genetics at NSU who led the study, said: 'Because sexuality is an essential part of human life, for individuals and society, it is important to understand the development and expression of human sexual orientation.
They found two regions with multiple genetic variants most strongly associated with sexuality. Men were asked to provide DNA by blood or saliva samples that were then analysed for variations in their genetic code. Sexual orientation of participants in the study was rated based on their self-reported sexual identity and sexual feelings. This examined the sexual orientation of 1,077 homosexual and 1,231 heterosexual men. In the latest study researchers at NorthShore University (NSU) HealthSystem’s Research Institute, based in Evanston, made the findings after conducting a genome-wide association study (GWAS). It vindicated the oft-repeated claims that ‘I was born this way’ but also opened frightening new possibilities for detection and discrimination. He showed that pairs of brothers who were openly gay shared a small region at the tip of the X, and proposed that it contained a gene that predisposes a male to homosexuality.
In 1993, American geneticist Dean Hamer found families with several gay males on the mother’s side, suggesting a gene on the X chromosome. The latest study is unlikely to settle this debate, but it is by no means the first to try and the claim that homosexual men share a ‘gay gene’ created a furore in the 1990s.
Debate has long raged among the scientific community over whether sexual orientation is biologically determined, the result of environmental causes or a combination of factors.