Gay Couple
Dwayne D. Beefe-Franqui (L) of Pensacola, Florida, holds on to his husband Jonathan. Reuters/Chris Tilley

Until now, the debate if homosexuality is genetic or due to environment rages. An experiment by a professor at the Ilia State University in Georgia believes there is a gay gene which half of the population carries.

Giorgi Chaladze used an individual-based computer genetic model which found that to keep the stable rate of homosexuality in large populations, 50 percent of the males and females must have the genes that affect sexuality, reports The Telegraph. It could explain the presence of homosexuality throughout human history and in all cultures, even if many gay men normally do not have many descendants who would directly inherit their genes.

The study, published in Archives of Sexual Behavior journal, says there is a tendency for gay men to come from large families, notes Chaladze elaborates, “The trend of female family members of homosexual men to have more offspring can help explain the persistence of homosexuality, if we also consider that those males who have such genes are not always homosexuals.”

Male homosexuality would be maintained in a population at low and stable frequencies if 50 percent if the males and more than half of the females carry the gay genes, Chaladze estimates. That indicates heterosexual men are carriers of the gene which explains why men who admit to gay behaviour and same-sex sexual attraction are higher than estimates who identify themselves as bisexuals or gays.

A 2013 study, led by Anthony Bogaert at the Brock University in Ontario, Canada, suggested the likelihood of a male becoming gay goes up with the number of brothers he has. Every older brother boosts the odds of a male child, by up to one-third, turning gay because of the mother’s changing immune responses to each baby.

About 1.8 percent of men in the US identify themselves as gay, while it is 1.1 percent in UK, although another 0.4 percent say they are bisexuals. In Australia, a Roy Morgan survey found that the percentage of gay population rose to 3.4 percent in its 2012-2014 survey, up from 3.1 percent in 2009-2011 and 2.4 percent in 2006-2008 poll.