Researchers in a latest study claim that they have found nine parts of the male genetic code that can determine whether a person is heterosexual or homosexual. The study authors said they have found evidence that environment also plays a role in man’s sexual orientation by altering the activity of certain genes.

The study’s lead researcher, Dr. Tuck Ngun of the University of California-Los Angeles (UCLA) during the annual meeting of the American Society of Human Genetics Thursday said that he and his team studied genetic material for 47 pairs of male identical twins.

Ngun said during the research his team identified the nine ‘epigenetic marks’. The term refers to areas of the epigenome, a set of chemical marks that lie between human genes and turns them on or off in response to certain stimuli.

The team claims that by studying the molecular data from the epigenetic marks, they were able to guess whether a twin pair was heterosexual or homosexual. They said they were 70% accurate in their results.

Ngun told the conference that this is the very first example of a predictoive model of sexual orientation which is based on molecular markers. “Sexual attraction is such fundamental part of life, but it's not something we know lot about at the genetic and molecular level. I hope that this research helps us understand ourselves better and why we are the way we are”, said Ngun.

Study researchers told that out of 47 sets of identical twins studied, 37 were pairs in which one twin was homosexual and the other was heterosexual. In the other ten pairs, both sets of twins were homosexual.