While epigenetic patterns are showing promise as a biomarker for certain traits, it’s still difficult to infer causality.
Straight gay test verification#
There needs to be verification before any firm conclusions can be drawn, he says.
![straight gay test straight gay test](https://quizow.com/wp-content/uploads/2021/10/Am-i-gay-quiz-o.jpg)
Since the associations have not yet been tested in a completely independent study population, the results should be considered no more than suggestive. “Studies that associate biomarkers with particular traits are notoriously prone to false positive results due to the tendency of these studies to find spurious associations that are down to sheer chance,” says Johnjoe McFadden, a molecular geneticist at the University of Surrey, UK. Other scientists are cautious about the results. When they tested their model on the remaining pairs of male twins, they found it correctly predicted sexual orientation 67 per cent of the time. Using the test results from 20 of the pairs, they developed a model to predict if a person is straight or gay based on the methylation patterns of their genes. “It could affect how neuronal circuits are patterned, and influence behaviour,” says Ngun, who presents the findings today at the American Society of Human Genetics annual meeting in Baltimore, Maryland. The other gene region implicated is responsible for making a protein that affects neuron function. These are important for a healthy immune system, but are also thought to affect sexual attraction. One of these genes is involved with the production of MHC II molecules. They found five sites– three in regions of “junk DNA”, the role of which is unclear, two in genes whose roles are relatively well established. They used an algorithm to search out gene regions in which methylation patterns differed significantly between the two groups. Next, Ngun and his colleagues looked at the genomes of homosexual and heterosexual volunteers. They ended up with a giant spreadsheet showing the levels of methylation across the genome of each twin, says Ngun. Ten of the twin pairs were both gay, while 37 pairs differed, with one brother identifying as gay and the other as straight. To investigate a potential role for epigenetics, Ngun and his colleagues looked for epigenetic modifications made to the genes of 47 sets of male twins. This might be down to epigenetic changes – the addition or subtraction of a methyl group to genes, which switches them on or off. A male pregnancy might leave some sort of marker behind that affects subsequent pregnancies.
![straight gay test straight gay test](https://i0.wp.com/post.healthline.com/wp-content/uploads/2019/11/What-Does-the-Kinsey-Scale-Have-to-Do-with-Your-Sexuality_-1296x1144-Infographic.20200128191535419-1296x1143.jpg)
“It seems as though the mother’s body is remembering the sex of previous pregnancies,” says Tuck Ngun at the University of California Los Angeles. The overall chance is still low, however, rising from around 2 per cent to just 6 per cent for a third son. For every male pregnancy a woman has, a subsequent son has a 33 per cent higher chance of being homosexual, although no one knows why. Other observations also suggest a genetic basis for sexual orientation, such as the mysterious fraternal birth order effect. The same region has been implicated in other studies of sexual orientation since, although researchers haven’t been able to single out “gay genes”. Perhaps the biggest splash was made in 1993 by Dean Hamer’s team at the National Cancer Institute in Bethesda, Maryland, when they found that gay brothers tended to share a sequence of five genetic markers in a region of the X chromosome.
![straight gay test straight gay test](https://i.ytimg.com/vi/ItSBI24EOV8/maxresdefault.jpg)
Over the last two decades, several studies have suggested that sexual orientation is, in part, down to our genes. “The predictive test needs replication on larger samples in order to know how good it is, but in theory it’s quite interesting.” “The scientific benefit to understanding is obvious to anyone with an iota of curiosity,” says Michael Bailey at Northwestern University in Evanston, Illinois.