Scientists, at the University of California, Los Angeles, have developed a specialized genetic test that, they claim, can predict the sexual orientation of a man, with nearly 70-percent accuracy. The newly-devised algorithm relies on the analysis of specific epigenetic markers to determine whether the male subject is straight or gay. What is more, a simple saliva sample can now uncover what might be a life-changing revelation for some.
Recently presented at the annual meeting of the American Society of Human Genetics (ASHG), in Baltimore, the research has attracted widespread attention, although certain sections of the scientific world have expressed concerns regarding the test’s reliability. In the study, the researchers worked with 47 pairs of identical male twins, 37 of which included one heterosexual sibling and one homosexual sibling. The remaining ten pairs, which formed the control group, consisted of two homosexual twins. Speaking about the project, Tuck C. Ngun, of UCLA’s David Geffen School of Medicine, said:
To our knowledge, this is the first example of a predictive model for sexual orientation based on molecular markers… 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.
Identical twins have the same genetic sequences, which means that the difference in sexual orientation may be the result of certain environmental factors, like DNA methylation. Consequently, the scientists looked for differing patterns of DNA methylation – a type of epigenetic mechanism that affects when and how a particular gene is expressed – in the genomes of the twins. Ngun added:
A challenge was that because we studied twins, their DNA methylation patterns were highly correlated. 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.
To help them sort through 400,000 odd epigenetic tags, the researchers built a highly-specialized algorithm, known as FuzzyForest. This technology allowed them to identify nine different regions in an individual’s genome, where methylation could be responsible for determining his sexual orientation. According to the team, the algorithm boasts an accuracy of around 70-percent. While the exact correlation between these methylated sections and the individual’s sexual orientation is yet not fully known, the scientists believe that further research will not only improve their understanding of the mechanism, but also enable them to enhance the test’s accuracy. Ngun said:
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.
One of the primary concerns, voiced by other scientists, is about the study’s limited sample size. For the test to be considered reliable, it needs to be conducted on larger groups of both homosexual and heterosexual males.