August 12, 2007
Study of Gay Brothers May Find Clues About Sexuality
By Robert Mitchum, Chicago Tribune
In Gregg Mierow's family, there were six boys, brothers who grew into two groups as they reached maturity: Three are gay, and three are straight.
Mierow stumbled upon a chance to help prove that hunch at the Northalsted Market Days festival four years ago. Spotting a banner reading, "Wanted! Gay Men with a Gay Brother," he stopped by the booth and volunteered for what he thought would be little more than a survey.
Instead, Mierow found himself part of the Molecular Genetic Study of Sexual Orientation -- the most extensive study yet to search for a genetic basis for homosexuality -- embarked upon by a team of Chicago researchers from local universities.
The scientists hope that by gathering DNA samples from 1,000 sets of gay brothers like the Mierows they will be able to find genetic linkages smaller studies failed to detect. They'll be recruiting brothers again at the Halsted Street festival this weekend.
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."
Although 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.
Studies that compare identical and fraternal twins for the frequency of a particular behavioral trait have consistently suggested there are both genetic and environmental causes of homosexuality. Identical twins, who share 100 percent of their genes, show a higher chance of both being gay compared with fraternal twins, who typically share the same family environment but only half their genetic code.
Researchers also have found physical traits that correlate with homosexuality, from the relative size of certain brain areas associated with sexual behavior to seemingly irrelevant characteristics like hair whorl direction and finger-length ratios.
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. The project received funding in 2001 and began recruiting subjects at gay pride festivals, through gay-oriented publications and on the Internet.
So far the Chicago researchers have obtained blood or saliva DNA samples and survey data from more than 600 brother sets, with several hundred other volunteers in the process of submitting one or the other. Sanders hopes to publish his findings from the first wave of DNA samples in a scientific journal sometime next year.
Sanders cautioned a linkage study can single out only regions of the genetic code, not individual genes.
"One of the advantages of linkage studies is that we don't have to know those things ahead of time," Sanders said. "It's a big advantage here because we don't know about the biology of sexual orientation yet, so we can find the genes first and then study the biology."
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."
The hunt for specific genes that affect sexual orientation may take several years, but the implications of this eventual finding are being fiercely debated already.
"I think this kind of research receives a lot more criticism and attention because people often think it has profound implications for social and moral decisions," Bailey said. "This is a controversial area. Even though it fascinates people, it scares people from the research end."
Researchers involved with the project believe finding a genetic linkage will help settle arguments over whether homosexuality is a choice or an innate trait.
"A lot of times people we talk to see this research as providing evidence for something they may [have] already had a notion for, that sexual orientation is influenced by pretty early events out of their control," said Sanders.
Sanders also suggested that as proof of biological predisposition grows, so too does acceptance and tolerance of homosexuals. A Gallup poll conducted in May indicated 42 percent of the surveyed population believe homosexuality is biologically determined -- the highest percentage witnessed in 30 years of polling.
Study volunteer Jason Palmer of Chicago said he hopes evidence of a biological source for homosexuality would change people's opinions on sexual orientation.
"Our strongest opponents are the religious right, many of whom feel that God does not make mistakes," Palmer said. "So if it's a genetic factor and proven, perhaps many of them will find an acceptance for homosexuals."
But some outside observers worry about how proof of a genetic component to homosexuality might be used politically and even medically.
"If you do research on any human behaviors that would allow us either to treat the behavior or to prevent it altogether by prenatal testing, you have got to ask yourself serious questions about societal context in which this type of research takes place," said Udo Schuklenk, a professor of philosophy at Queen's University in Kingston, Ontario.
Critics fear identifying a biological component will lead to prenatal testing and perhaps even treatments for homosexuality. While both Sanders and Bailey expressed doubt about the scientific feasibility or public demand for such applications, Schuklenk suggested they were not considering the worldwide implications.
"I understand why U.S. gays want to know why gay people are gay and understand where they are coming from -- there are legal reasons, and the agenda is progressive within the context of the U.S.," said Schuklenk. "What worries me is that they show a complete disregard of repercussions of research on the international scale, for gay people in societies where civil rights are not as well-protected."
Mierow said he considered the potential negative ramifications when he volunteered for the study but trusted that changing social views on homosexuality will intervene.
"I hope that by the time science gets to the point [of prenatal testing], society would have progressed enough to not have those feelings," Mierow said. "I feel like I have more trust in science. It seems like a lot of the bigotry is coming out of religion."
"People who say that, 'We shouldn't know X because knowing X is dangerous,' to me those are the dangerous people," Bailey added. "They have provided no good evidence that knowing things is risky; ignorance is what messes us up."
For now, these discussions will remain largely theoretical until the results of Sanders' study, as well as others in progress around the country, begin to be released.
As Bailey noted, the results won't just add to knowledge about the roots of homosexuality, they may also answer more general questions about gender and sexuality.
"Knowing what causes sexual orientation is important scientifically," he said. "It's an important aspect of who we are and will provide knowledge about the development of gender, how men and women differ from each other."