Epigenetic Marks Tied to Homosexuality

In a recent study of male twins, nine methylation sites helped researchers predict a person's sexual orientation. Throughout the study, it had been examined its genome and determining whether the individuals are methylated can peg sexual orientation with nearly 70 percent accuracy. The idea of epigenetics influencing sexual orientation had been proposed several years ago, but had been more recently examined in today's generation. Researchers had found that methylation status of nine regions in the genome could identify sexual orientation with a significant percent accuracy. Margaret McCarthy, a scientist at the University of Maryland School of Medicine stated, "This study provides a major step forward in our understanding of how the brain can be affected by factors outside of the genome. It is also possible that the experience of being a homosexual or a heterosexual has itself impacted the epigenetic profile. But regardless of when, or even how, these epigenetic changes occur, their findings demonstrate a biological basis to partner preference". It is also true that pinpointing the exact origins of this biological basis is a thorny issue. More work must be done to uncover the functional significance of the methylation profiles. Some scientists expressed caution in interrupting early data from a small study.

Additionally, twin studies and family trees provide strong evidence that sexual orientation is at least partially genetic. When one identical twin is gay, there is about 20% chance that the other will be as well. Due to the fact that this rate is not 100%, it is thought that environmental factors play a role as well and this can be characterized as the 'older brother effect', which is that chance is a man being gay increases by 33% for each older brother he has. This reason is not clear, but one hypothesis holds that the mother's immune system begins to react against male antigens and alter the fetus's development. In my opinion, I think a genome being able to tell if a person is homosexual or heterosexual is absolutely outrageous. I always believed a persons sexuality preference is their personal desire, not determined from a gene in your brain. I also think that the topic is not researched enough where it can prove this theory to be accurate.  

Link to article:

http://www.the-scientist.com/?articles.view/articleNo/44201/title/Epigenetic-Marks-Tied-to-Homosexuality/

Link to alternative article:

http://www.nature.com/news/epigenetic-tags-linked-to-homosexuality-in-men-1.18530

New Test Can Predict a Man's Sexual Orientation

Researchers have recently developed a test that is said to be able to predict a man's sexuality with up to 70% accuracy. The test uses an algorithm that can identify patterns of DNA methylation, a molecular modification to DNA that controls gene expression, across nine regions of the human genome that researchers believe might be related to sexual orientation. DNA methylation occurs as a result of environmental factors, such as exposure to chemicals, stress, diet, and exercise.

The recent study of the process builds upon previous studies that have shown that a person's sexuality may be determined by the activity of certain genes and that epigenetic differences are one of the main reasons that identical twins who share all their genes can vary in homosexuality. In the study the team of researchers employed 37 pairs of identical male twins, where one was homosexual and one was heterosexual, and another 10 pairs, where both males were homosexual. They were then capable of pinpointing specific DNA methylation patterns that might be associated with sexual orientation utilizing an algorithm called FuzzyForest. From this, the researchers were able to identify these DNA methylation patterns in 9 specific areas of the human genome that could determine each twins sexuality with 70% accuracy. These areas were capable of being defined to the base pair level.

The researchers now say they are unable to explain how the DNA methylation in these specific areas of the human genome can actually influence a man's sexuality, but they plan to address the concept in further studies. Meanwhile, they will continue to test the accuracy of the algorithm in a larger population of men.

I find this study very interesting. Given that the genetic and molecular basis of our sexual orientation is not well known, the study is a huge step in helping us understand ourselves and why we are the way we are.

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New Evidence Shows that Genetics Influence Sexuality

A new study that involved 800 homosexual brothers and twins has shown that 2 genes are linked to male sexuality.  One of these genes is on the X chromosome while the other is on a different chromosome.  While this does not give definitive proof that sexuality is determined by genetics, it brings many people one step closer to the accepting the idea that sexuality is not a choice.  For a long time, people have debated the idea of nature vs. nurture; which one determines sexuality? Many people believe that being gay is a choice or that the environment influences sexuality.  This study has brought forward evidence that sexuality is determined by genetics, just like hair color.  It is a possibility that the environment influences sexuality when a person has a genetic predisposition for a certain sexuality.

I think it is morally wrong to believe that sexuality is a "choice" and that a person has chosen to be attracted to men, women, or both.  This study gives more evidence that people do not have a choice in their sexuality and who they are attracted to.