A new study has suggested that male homosexuality is much more genetically determined than previously thought, and is directly related to the fecundity of female relatives.
“But it’s worth noting that the data on the sexuality of family members may be unreliable, so more studies are likely to be needed to confirm these findings,” she says.
Even if the maternal factors identified by Camperio-Ciani’s team are linked with male homosexuality, the research team’s calculations suggest they account for only about 14% of the incidence.
They found that female relatives of gay men had more children on average than the female relatives of straight men.
But the effect was only seen on their mother’s side of the family.
Mothers of gay men produced an average of 2.7 babies compared with 2.3 born to mothers of straight men.
And maternal aunts of gay men had 2.0 babies compared with 1.5 born to the maternal aunts of straight 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.
Their findings also support earlier findings that when mothers have several sons, the younger ones are progressively more likely to be gay.
This might be due to effects changes to the mother’s immune system with each son they carry.
Male homosexuality is inborn and may be triggered by a gene carried by mothers, new findings suggest.