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A new DNA test can predict sexual orientation with 70% accuracy, based on epigenetic modifications, researchers have claimed.
A team of experts from the University of California, Lo Angeles made this discovery after analyzing 47 pairs of identical male twins. 37 of the pairs included one heterosexual and one homosexual sibling, while 10 other pairs in a control group were entirely homosexual.
The scientists collected samples of saliva from every subject, in order to identify potential differences between gay and straight individuals. Since monozygotic twins are genetically nearly identical, researchers focused on variations resulting from the presence of epigenetic markers.
This process of DNA methylation occurs when gene expression suffers modifications, displaying oscillating levels of activity. For example, one gene can be switched on or off, or it can function just partially, as a result of environmental factors like stress, chemical exposure, eating habits and physical exercise.
DNA methylation helps explain why only 20% of identical twins actually share the same sexual preferences, despite possessing the same genetic makeup.
In order to assess these epigenetic modifications, researchers invented an algorithm named FuzzyForest, which analyzed 400,000 data points. While DNA methylation among monozygotic twins was closely correlated, 9 specific regions of the genome were detected, and it appears they can predict the respondents’ sexual orientation.
According to the experts, these epigenentic components which influence how DNA code is translated are 70% accurate in determining the actual sexuality of an individual.
“To our knowledge, this is the first example of a predictive model for sexual orientation based on molecular markers”, declared study co-author Tuck C. Ngun.
As researchers explained, prior experiments had identified wider sections of chromosomes that played a role in influencing heterosexuality or homosexuality. Now, much more limited and precise portions have been discovered, which seem to provide “a biological basis for partner preference”.
For now, the findings are considered preliminary, since they haven’t yet been published in a peer-reviewed journal. They were only presented during the annual meeting of the American Society of Human Genetics in Baltimore, Maryland.
However, they have already stirred controversy, because of the ground-breaking allegations they seem to make. Critics insist that more research has to be conducted in order to support the claims, especially given the fact that sample size isn’t significant enough, so results may be unreliable.
A study of a larger scale should be used, in order to determine if epigenetic signatures serve indeed as predictors of sexuality, according to Christopher Gregg, assistant professor of neurobiology, anatomy and human genetics at the University of Utah.
Meanwhile, the study authors are refining their algorithm and delving deeper into this field, in order to better explain exactly how the process of DNA methylation impacts sexual orientation.
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