Male homosexuality is inborn and may be triggered by a gene carried by mothers, new findings suggest.
Evolutionarily speaking, homosexuality as a trait would not last because it discourages reproductive sex with women and therefore procreation.
However a new study, published in The Journal of Sexual Medicine, found a correlation between gay men and their mothers and maternal aunts, who are prone to have significantly more children compared to the maternal relatives of straight men.
Researchers led by Andrea Camperio Ciani, from the University of Padova in Italy, say that the findings of the link between homosexuality and female fertility strongly support the "balancing selection hypothesis," which suggests that a gene which causes homosexuality also leads to high fecundity or reproduction among their female relatives.
The team noted that the "gay man gene" may not get passed down directly, but instead survive through the generations through future generations making their male inheritors gay.
Researchers analyzed the personality and fecundity of 61 females who were either mothers or maternal aunts of homosexual men to 100 females who were mothers or aunts of heterosexual men.
Originally the team thought the reason why women who inherited the "gay man gene" might have more babies is simply because it increased androphilia, or attraction to men, thus making the male inheritors homosexual and the female inheritors more promiscuous.
However, after analyzing the personal characteristics of 161 female maternal relatives of homosexual and heterosexual men, researchers changed their hypothesis and suggested that rather than making the women more attracted to men and therefore more promiscuous, the "gay man gene" appears to make female inheritors more attractive to men.
"High fecundity, that means having more babies, is not about pleasure in sex, nor is it about promiscuity. The androphilic pattern that we found is about females who increase their reproductive value to attract the best males," Camperio Ciani told Life's Little Mysteries.
The team found that the gene appeared to make women more fertile, have fewer gynecological disorders and fewer pregnancy complications. The findings also suggest that gene led to women who were funnier, happier, more extroverted and more relaxed, leading them to have fewer family problems and social anxieties.
"If sexually antagonistic genetic factors that induce homosexuality in males exist, the factors might be maintained in the population by contributing to increased fecundity greater reproductive health, extraversion, and a generally relaxed attitude toward family and social values in females of the maternal line of homosexual men," researchers wrote.