Monday, January 7, 2013

Epigenetics may explain sexual preferences

After homosexuality was recognized as a natural phenomenon in the scientific world, researchers have begun looking at the origins of same-sex preferences. Structural differences in the brain tell us that sexuality is something that is developed early in life, and is not something that can be learned, as religious institutes often like to exclaim. This biological background lead to the belief that there must be genes that influence homosexuality, but a group of European and American scientists shows that differences in the structure of the DNA are more suited towards explaining this phenomenon.

How the structure of the DNA relates to activity of genes is a field of study dubbed epigenetics. It deals with factors that affect genetics without actually changing something to the genetic code. This includes structural changes to the DNA, making it more open or closed, resulting in more or less genetic activity, respectively. In the present study, scientists found epigenetic markers that are of influence when it comes to sexual preferences.
DNA (from right to left) winding into a certain structure. Things that affect the structure may also affect the activity of genes.
One of the most important groups of molecules when it comes to sexual development are the androgens. Testosterone is perhaps the most well-known in this group, and it works by stimulating the development of male features. During embryonic development, a sex mechanism makes sure that males are susceptible to androgen stimulation, while females are affected less or differently. This results in sexual differentiation, both in mind and body, but things are not that clear-cut and simple.

What the scientists propose is that homosexuality has something to do with sensitivity towards androgens. Epigenetic changes may influence this sensitivity: it is hypothesized that androgen sensitivity can specifically alter sexual preferences. That means an embryo can still grow to be a fully-functioning male, while having same-sex preferences. This would also explain why homosexuality is, to some extent, inheritable, and provide additional evidence towards the biological origin of sexual preferences.

Despite being a touchy subject, many studies have been performed on the topic of sexual preferences. It is now clear that sexuality forms in the brain and that embryonic development lays the foundation of one's preferences. While the epigenetic view on homosexuality is something that needs to be expanded on in order to elucidate how big of a role it plays, it is clear that the evidence for homosexuality being a normal natural phenomenon is increasing.

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