New research published in the Quarterly Review of Biology suggests genetics which make a person more likely to be gay are passed from fathers to daughters and mothers to sons.
Previous studies have already shown that homosexuality runs in families, leading most researchers to presume a genetic underpinning of sexual preference.
But to date, no major gene for homosexuality has been found despite numerous studies searching for a genetic connection.
However, researchers from the US National Institute of Mathematical and Biological Synthesis now suggest homosexuality has an epigenetic link, not a genetic one.
The study reports that “sexually antagonistic” epi-marks, sometimes carried over generations, are transmitted through the opposite gender, such as father to daughter or mother to son during foetal development.
“Transmission of sexually antagonistic epi-marks between generations is the most plausible evolutionary mechanism of the phenomenon of human homosexuality,” said study co-author and University of Tennessee-Knoxville researcher Sergey Gavrilets.
William Rice, an an evolutionary biologist at the University of California Santa Barbara and lead author of the study, said epi-marks can determine the development of homosexuality in the offspring of heterosexual parents.
“There is compelling evidence that epi-marks contribute to both the similarity and dissimilarity of family members, and can therefore feasibly contribute to the observed familial inheritance of homosexuality and its low concordance between [identical] twins,” the Mail reports Mr Rice as saying.