Epigenetics and homosexuality
Biologists have learned to predict sexual orientation by DNA
The new algorithm, which takes into account epigenetic information from only nine sections of the human genome, makes it possible to predict the sexual orientation of men with an accuracy of 70 percent. The author of the discovery told about this at the annual congress of the American Society of Human Genetics, which takes place on October 6-10, 2015 in Baltimore.
The scientists worked with DNA methylation – modification of a molecule without changing its nucleotide sequence – throughout the entire length of the genome in pairs of identical male twins. Although the DNA of such twins is the same, various environmental factors lead to differences in methylation as people live. Thus, scientists were able to remove the effects of "pure" genetic differences and identify the effects of methylation.
In total, the researchers analyzed the DNA of 37 pairs of twins, one of whom was homosexual, and ten pairs where both twins adhered to non-traditional sexual orientation. The main problem was the high correlation of the DNA methylation features of the study participants. This, as well as a huge amount of data, made it difficult to determine differences significant for sexual orientation.
Scientists were able to solve this problem using a machine learning algorithm called FuzzyForest. They found that methylation features in nine small sites scattered throughout the genome can be used to predict sexual orientation with a probability of up to 70 percent.
"As far as we know, this is the first model capable of predicting sexual orientation based on molecular markers. Previously, scientists have already identified vast areas of chromosomes associated with sexual orientation. But our approach allowed us to name specific sites – up to individual base pairs," the author of the study, Tuck C. Ngun, said (at the annual congress of the American Society of Human Genetics in the report Epigenetic Algorithm Accurately Predicts Male Sexual Orientation – VM).
More research will be needed to understand exactly how DNA methylation at these sites is related to sexual orientation. Now scientists are testing their algorithm on a more representative sample of men (not twins).
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09.10.2015