Homosexuality may be genetic, but not in the traditional sense of the word. According to researchers from the University of Tennessee, sexual preference may be significantly influenced by epigenetic triggers, or chemical biomarkers, which instruct genes to behave in a certain manner, rather than a specific gene.
“In spite of enormous effort people have put toward finding gay genes, nobody has been able to identify them,” study co-author Sergey Gavrilets, joint professor of math and ecology and evolutionary biology and NIMBioS’s associate director for scientific activities, explained to WBIR. “Our study proposes that homosexuality is influenced by fetus sensitivity to androgen and testosterone, the different types of male hormones that cause sexual development. It is more like a power switch that is left on and passed down from one parent to offspring of the opposite sex.”
Gavrilets and his team theorized that homosexual individuals received epigenetic chemicals that would normally be erased from generation to generation. The researchers explained such chemical biomarkers from a mother would make a child very feminine, whereas the biomarkers from the father’s side would make a child very masculine.
“…Sometimes the switches can be passed down to the opposite sex instead of being erased. So if a mother passes her epi-marks to a son, then the male will be less sensitive to testosterone and more feminine. Or if a daughter inherits her father’s epi-marks then it can cause the female to become masculinized and affect sexual behavior,” Gavrilets said.
The research, which was published in The Quarterly Review of Biology, did not prove homosexuality come solely from inherited biomarkers, but rather demonstrated a plausible process which would link sexual preference to heredity.
It is one of the most feasible theories to date, explained Gavrilets, because if a specific gene were tied to homosexuality, eventually it would disappear from the population as people who prefer the same sex cannot reproduce without medical intervention.
“Transmission of sexually antagonistic epi-marks between generations is the most plausible evolutionary mechanism of the phenomenon of human homosexuality,” said the study co-author in a university press release. “Previous studies have shown that homosexuality runs in families, leading most researchers to presume a genetic underpinning of sexual preference; however, no major gene for homosexuality has been found despite numerous studies searching for a genetic connection.”