For ages, sexual scientists have theorized the existence of a "gay gene" — that is, a genetic basis for homosexuality to help explain why some people are gay and others are not.
But according to an international research study just published in the Quarterly Review of Biology, scientists will never find "a gay gene" because homosexuality isn't caused by genes, but is influenced rather by nanoscopic structures laying on top of our genes; structures called "epi-marks."
Epi-marks determine how our genes express themselves in response to environmental factors in and outside of the womb. Put another way, genes are like Play-Doh and epi-marks are like the Fun Factory molds that determine the shape the Play-Doh takes when you add a little pressure.
In the case of homosexuality, the researchers posit that epi-marks on top of our genes determine just how much each fetus gets affected by the male and female sex hormones (testosterone and estrogen) which determine a child's genitals, gender identity and sexual orientation.
Researchers think that the epi-marks of gay people may have exposed their fetal brains and bodies to a mixture of male and female hormones that resulted in a homosexual orientation rather than a heterosexual one.
That is, hormones and epi-marks could play a bigger role in sexual orientation that just flat-out genes.
Though the study is filled with complex science jargon like "chromatin structure," "nucleosome repositioning" and "DNA methylation," the basic conclusions are easy enough to understand.
They could also explain why some people end up bisexual, transgender or as gender non-conformists — it all has to do with whatever hormonal cocktail you drank while sitting in the womb.