Adding to decades of speculation and research a new study suggests that male homosexuality is at least partly genetic.
Scientists at Northwestern University in Chicago say that a gay man’s DNA contributes around 40% toward him being gay while the other 60% of his sexuality is probably based on environmental or other factors.
The researchers studied 400 sets of twins to asses to what extent homosexuality is a genetic trait.
They found that gay men have shared genetic signatures on parts of the X chromosome, which are likely to increase their predisposition to become gay, reports The Telegraph.
The scientists say, however, that this genetic similarity is not determinative, and that homosexuality is also largely influenced by other factors, which could include hormonal influences in the mother’s womb.
Researcher Dr Michael Bailey commented: “Sexual orientation has nothing to do with choice. Our findings suggest there may be genes at play – we found evidence for two sets that affect whether a man is gay or straight.”
Dr Alan Sanders, associate Professor of Psychiatry at Northwestern University, added that “We don’t think genetics is the whole story. It’s not. We have a gene that contributes to homosexuality but you could say it is linked to heterosexuality. It is the variation.”
While the research could lead to a future test for homosexuality in unborn babies it would not be reliable and would only suggest the increased possibility that the child would turn out gay.
So far no similar shared genetics signatures have been found among lesbian women.
The nature vs. nurture debate on whether people are born homosexual or become gay as they grow up has always been a contentious issue.
In 2012, other scientists suggested that homosexuality might be passed on by parents, from father to daughter or mother to son, not through their genes but through switches called epi-marks that regulate gene expression .
Scientists have also found that the brains of homosexuals have slight structural differences to those of ‘straight’ people of the same gender and also discovered that the more older brothers a man has, the greater the chances of him being gay.
Many anti-gay groups refuse to accept that homosexuality could be a natural phenomenon and justify their homophobia with the assertion that it is somehow “learned” after birth.
In Africa, for example, it is widely believed that people are somehow “indoctrinated” into homosexuality. Last month, Uganda’s President Yoweri Museveni said that he would make a decision on signing his country’s draconian Anti-Homosexuality Bill based on whether or not scientists could prove to him that homosexuality is “normal”.
While no conclusive gay gene has yet been discovered, research increasingly confirms that homosexuality appears to come about in large part through genetic aspects as well as a result of developments in the womb and that it is simply another aspect of human sexuality.