Researchers at the University of California in Los Angeles followed 37 pairs of identical male twins, in which one was homosexual, the other not. They followed an additional 10 sets of twins where both were homosexual. It turned up that only 20 percent of identical twins are both gay, so researchers thought there must be some other causes, which are not inherited.

Findings then also suggested that the presence of specific epigenetic markers in nine areas of the human genome could go a long way toward predicting a preference for homosexuality.

Epigenetics – the field that deals with how DNA behaves after birth – formed the central core of the studies’ approach. While we know DNA to be a sort of manual for how the body looks and functions, epigenetics acts like a highlighting marker, accentuating certain traits. This added layer of information is known to be triggered by environmental factors – everything from chemical exposure to stress and child abuse.

“To our knowledge, this is the first example of a predictive model for sexual orientation based on molecular markers,” UCLA postdoctoral researcher in gender-based biology Tuck Ngun said in a statement.

The research, which hasn’t been published yet, was presented on October 8 at the annual meeting of the American Society of Human Genetics.

The problem that immediately arose after the research was made public indicates a lack of conclusive consensus in the scientific community. While the gay question has intrigued scientists for some time, they can’t agree on the one hand, with the potential accuracy of such an epigenetics test; on the other, researchers can’t agree on exactly what part the environment plays with regard to someone being or becoming gay.

Some British scientists believe the UCLA claim to precision to be a bit “bold.” Ngun himself agrees that the research is inconclusive. As with other similar research, he sees a correlation between factors, but nothing to suggest a cause.

“There is absolutely nothing that’s well accepted that defines a genetic basis of homosexuality,” Harvard University geneticist Dr. Robert Green said, after calling the new claims an “intriguing finding,” according to Healthline.com.

Other researchers also had doubts. “The question as to whether that prediction is going to be useful outside of the small number of twins in the study is really unclear,” genetics professor at the University of Utah, Dr. Christopher Gregg, said, as cited by Reuters. Gregg did, however, praise the researchers’ “state-of-the-art methodology.”

The sentiments were shared by others, who claimed such findings normally fall apart when bigger groups are tested.

“One thing you can clearly see is that the sample size is too small. They don’t have enough power to make that claim,” said Dr. Peng Jin, professor of human genetics from Emory University in Atlanta.

“What they are seeing may be certain correlations, but I don’t think they have what they claim, which is a predicting model,” he added. “It’s definitely an interesting observation, but … I don’t want the general audience to misinterpret whatever they are presenting.”

Professor of genetics Darren Griffin, at the University of Kent in the UK, added, according to The Telegraph, that “while there is strong evidence in general for a biological basis for homosexuality my personal impression has always been one of a multiple contributory, including life experiences.”

Griffin believes the association may not be as plain as it first seems, “as the complete story unfolds.”

“To claim a 70 per cent predictive value of something as complex as homosexuality is bold indeed. I wait with baited breath for a full peer-reviewed article.”

The researchers at UCLA are already at work on a new study with a larger sample.