Researchers study DNA of gay brothers for clues

I actually wanted to participate in this study described in a Houston Chronicle article (http://www.chron.com/disp/story.mpl/nation/5082744.html), but my brother refuses to do so - he apparently thinks participating would mean that he is gay, whereas the study - I have filled out the questionnaires, etc., and read the study description and talked with Dr. Alan Sanders (mentioned below) - merely wants two (2) brothers, at least one of whom is gay so that there is a basis of comparison. I will ask him again to reconsider, but I will not be holding my breath. Personally, I believe that there is some type of genetic component to sexual orientation. For obvious reasons, I would love to have it scientifically confirmed that sexual orientation is genetic and, therefore, NOT a choice so that the Christianist "cure" programs could be shut down once and for all. Here are some highlights from the article:

The results may ignite controversy, the researchers acknowledge, both by providing ammunition in the raging cultural war over homosexuality and by raising fears about ethically questionable applications like genetic profiling and prenatal testing. But, they argue, the research is essential to our biological understanding of sexual behavior.

"If there are genetic contributions to sexual orientation, they will not remain hidden forever — the march of genetic science can't be stopped," said Timothy F. Murphy, bioethicist adviser to the study. "It's not a question of whether we should or should not do this research, it's that we make sure we're prepared to protect people from insidious uses of this science." While the question of whether homosexuality is a choice remains a hot topic for pundits, scientists are largely in agreement that sexual orientation is at least partially determined by biology.

Inspired by the accumulating circumstantial evidence of genetic factors, researchers in the early '90s began trying to narrow down the wide expanse of DNA to a few promising regions. By comparing the genetic codes of gay brothers, who also share 50 percent of their genes, a "linkage study" tries to detect areas that show up in both men at a frequency higher than chance, suggesting one or more genes in that region might be linked to sexual orientation.

In 1993, geneticist Dean Hamer announced his group had found such a region on the X chromosome, which males inherit from their mothers. But the number of brother pairs used in the study was small and subsequent studies failed to replicate Hamer's findings, throwing the result into question.

"In complex gene scenarios, people figured out that you need a larger sample size in order to get reasonable statistical power," said Dr. Alan Sanders, a psychiatrist at Evanston Northwestern Healthcare and the leader of the current study. To increase the chances of finding genetic areas associated with homosexuality, Sanders proposed assembling almost 10 times the sibling pairs of previous studies.

At this point, the researchers do not know what types of genes they may find; they could be related to hormones, sexual development or a completely unexpected system. "The genes would probably be doing their work by affecting sexual differentiation of the brain during prenatal life," said J. Michael Bailey, a Northwestern University psychology professor involved with the project. "But what scientists are increasingly appreciating is that genes can affect a trait in ways you could never have guessed."