Scientists tie homosexuality to chemical markers that accompany DNA.

[DetlefK]

http://throb.gizmodo.com/report-dna-markers-accurately-predict-male-homosexuali-1735515589
http://www.nature.com/news/epigenetic-tags-linked-to-homosexuality-in-men-1.18530

First:
DNA is not a blueprint. It's a step-by-step "How-to"-manual. In a given situation, the body reacts by activating the appropriate "step", a gene, from the DNA. A copy of the instructions is made in the form of a strand of m-RNA. And the instructions on the m-RNA are then put to work with the aid of r-RNA and t-RNA, constructing a protein, a "chemical machine", that is tailor-made for taking care of this specific situation.

That's not the whole story: There are chemical markers attached to the DNA. They influence how the genes get expressed.

Scientists compared 37 pairs of identical twins where one was gay and one was not, and 10 pairs of identical twins where both were gay.

To search for factors that could mediate a link between environment and genes, geneticist Eric Vilain at the University of California, Los Angeles (UCLA), and his colleagues looked at epigenetic markers — chemical changes to DNA that affect how genes are expressed, but not the information they contain. These 'epi-marks' can be inherited, but can also be altered by environmental factors such as smoking, and are not always shared by identical twins.

The researchers collected DNA samples in saliva from 37 pairs of identical twins in which only one twin was gay, and 10 pairs in which both were gay. By scanning the twins’ epigenomes, the researchers found five epi-marks that were more common among the gay men than in their genetically identical straight brothers. An algorithm they developed based on the five epi-marks could correctly predict the sexual orientation of men in the study 67% of the time.

...

Vilain is not surprised to find that epigenetics is associated with sexual orientation, although he says it is too early to try to directly link the epi-marks to any particular environmental exposure or the expression of a specific gene.

...

Vilain acknowledges limitations of the study — for instance, epigenetic markers differ between tissues in the body, and those in the brain are probably most relevant to sexual orientation.

...

“We already know there is no 'gay gene',” says William Rice, an evolutionary geneticist at the University of California, Santa Barbara. If there were, he says, it would have turned up in one of the massive studies that scan the whole genome for variants shared between gay people.



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IMO, the fact that the chemical markers can change might also explain the phenomenon of "late-blooming lesbians", heterosexual women that turn homosexual at a certain age.

And it would explain why there are different degrees of bisexuality between heterosexual and homosexual.

[xocet]

1. Interesting research....

Here is a NOVA ScienceNow video from 2007 that discusses epigenetics:

http://www.pbs.org/wgbh/nova/body/epigenetics.html

[AlbertCat]

2. Scientists tie homosexuality to chemical markers that accompany DNA.

Let's hope they used a tasteful knot.


Interesting.... the chemical environment your genes live in and how it effect them.