Homosexuality genetic or environmental? Researchers find new insight

Is homosexuality, which is found in up to 10 percent of people, a matter of genes, or a matter of environment? A new study may have found new insight into this lengthy debate. Researchers at the National Institute for Mathematical and Biological Synthesis (NIMBioS) said the trait may not be in the DNA sequence but in how genes are expressed, according to an article on Time.com. They added the expressions may have environmental roots, so may not be permanent enough to be passed from parent to child, but can be passed occasionally. "It’s not genetics. It’s not DNA. It’s not pieces of DNA. It’s epigenetics. The hypothesis we put forward is based on epigenetic marks," said Sergey Gavrilets, a NIMBioS researcher and an author on the paper that outlines the new theory of homosexuality. The researchers' new theory suggests that homosexuality is caused by epigenetic marks, or “epi-marks,” related to sensitivity to hormones in the womb. While experimental evidence is lacking for now, Gavrilets says he is reasonably confident that the theory is sound. “It’s compatible with the [existing] data. Plus it’s supported by mathematical modeling,” he said. Gavrilets added some scientists have expressed “strong interest” in new experiments that will test the hypothesis. The experiments will seek to see how often such epi-marks may arise among men and women, and how often they are saved from one generation to the next. In turn, the work might also explain the extent to which epi-marks can influence sexual behavior. Responding to testosterone Gavrilets and his colleagues believe gene expression may regulate how a fetus responds to testosterone, and that epi-marks may help to buffer a female fetus from high levels of testosterone by suppressing receptors that respond to testosterone. While these epi-marks are erased after they are activated, if those marks are passed down to the next generation, the same epi-marks that protected a man in utero may cause oversensitivity to testosterone among his daughters. Also, the epi-marks that protected a woman in utero may lead to undersensitivity to testosterone among her sons. Synthesizing principles Time.com said the new theory may synthesize well-tested  principles with cutting-edge research in molecular biology and biological computation. But for now, the researchers' work is still controversial, with Gavrilets saying he and his colleagues have been criticized from both sides. He said they had been questioned by conservatives not happy with people searching for a biological basis to homosexuality, and some in the gay and lesbian community, who feel they should not require a scientific justification for who they are. “It’s been a controversial topic. There is a lot of misconception in the world about the topic of homosexuality,” Gavrilets said. Still, he said one of the roles of science is "to clear up misconceptions, to explain different phenomena or different patterns.” — LBG, GMA News