New research suggests homosexuality really is linked to one's DNA and can be predicted through a genetic analysis. A team of researchers were able to predict the sexual orientation of males with up to 70 percent accuracy using an algorithm that analyzed only nine regions of the human genome, the American Society for Human Genetics reported.
"To our knowledge, this is the first example of a predictive model for sexual orientation based on molecular markers," said Tuck C. Ngun, first author on the study and a postdoctoral researcher at the David Geffen School of Medicine of the University of California, Los Angeles.
To make their findings, the researchers looked at patterns of DNA methylation (a molecular modification to DNA that influences how a gene is expressed) across the genomes of pairs of male identical twins. Identical twins are born with the same genetic sequences, but environmental factors can cause differences in how this DNA is methylated. Studying identical twins allowed the researchers to control for genetic differences that could lead to false information. The study included 37 pairs of twins in which one twin was homosexual and the other was heterosexual and 10 pairs in which both twins were homosexual.
"A challenge was that because we studied twins, their DNA methylation patterns were highly correlated," Ngun said. "The high correlation and large data set made it difficult to identify differences between twins, determine which ones were relevant to sexual orientation, and determine which of those could be used predictively."
In order to analyze the data, the researchers employed a machine learning algorithm called FuzzyForest. The algorithm revealed methylation patterns in nine small regions of the genome could predict sexual orientation with an accuracy of 70 percent.
"Previous studies had identified broader regions of chromosomes that were involved in sexual orientation, but we were able to define these areas down to the base pair level with our approach," Ngun said.
In the future, the researchers hope to discover exactly why DNA methylation in those regions is linked to sexual orientation.
"Sexual attraction is such a fundamental part of life, but it's not something we know a lot about at the genetic and molecular level. I hope that this research helps us understand ourselves better and why we are the way we are," Ngun concluded.
The findings were presented at the American Society of Human Genetics (ASHG) 2015 Annual Meeting in Baltimore.
