Study of gay brothers may find clues about sexuality

In Gregg Mierow’s family, there were six boys, brothers who grew into twogroups as they reached maturity: Three are gay, and three are straight.
“It seems innate to me,” Mierow, who works in advertising and as a yogateacher in Chicago, said of his homosexuality. “It doesn’t seem like there’sany choice involved, and it seemed very clear even when we were very young.”
Mierow stumbled upon a chance to help prove that hunch at the NorthalstedMarket Days festival four years ago. Spotting a banner reading, “Wanted! GayMen with a Gay Brother,” he stopped by the booth and volunteered for what hethought would be little more than a survey.
Instead, Mierow found himself part of the Molecular Genetic Study of SexualOrientation – the most extensive study yet to search for a genetic basis forhomosexuality – embarked upon by a team of Chicago researchers from localuniversities.
The scientists hope that by gathering DNA samples from 1,000 sets of gaybrothers like the Mierows they will be able to find genetic linkages smallerstudies failed to detect. They’ll be recruiting brothers again at the HalstedStreet festival this weekend.
The results may ignite controversy, the researchers acknowledge, both byproviding ammunition in the raging cultural war over homosexuality and byraising fears about ethically questionable applications like genetic profilingand prenatal testing.
But, they argue, the research is essential to our biological understandingof sexual behavior.
“If there are genetic contributions to sexual orientation, they will notremain hidden forever – the march of genetic science can’t be stopped,” saidTimothy F. Murphy, bioethicist adviser to the study. “It’s not a question ofwhether we should or should not do this research, it’s that we make sure we’reprepared to protect people from insidious uses of this science.”
Although the question of whether homosexuality is a choice remains a hottopic for pundits, scientists are largely in agreement that sexual orientationis at least partially determined by biology.
Studies that compare identical and fraternal twins for the frequency of aparticular behavioral trait have consistently suggested there are both geneticand environmental causes of homosexuality. Identical twins, who share 100percent of their genes, show a higher chance of both being gay compared withfraternal twins, who typically share the same family environment but only halftheir genetic code.
Researchers also have found physical traits that correlate withhomosexuality, from the relative size of certain brain areas associated withsexual behavior to seemingly irrelevant characteristics like hair whorldirection 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 ofDNA to a few promising regions. By comparing the genetic codes of gaybrothers, who also share 50 percent of their genes, a “linkage study” tries todetect 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 sexualorientation.
In 1993, geneticist Dean Hamer announced his group had found such a regionon the X chromosome, which males inherit from their mothers. But the number ofbrother pairs used in the study was small and subsequent studies failed toreplicate Hamer’s findings, throwing the result into question.
“In complex gene scenarios, people figured out that you need a largersample size in order to get reasonable statistical power,” said Dr. AlanSanders, a psychiatrist at Evanston Northwestern Healthcare and the leader ofthe current study.
To increase the chances of finding genetic areas associated withhomosexuality, Sanders proposed assembling almost 10 times the sibling pairsof previous studies. The project received funding in 2001 and began recruitingsubjects at gay pride festivals, through gay-oriented publications and on theInternet.
So far the Chicago researchers have obtained blood or saliva DNA samplesand survey data from more than 600 brother sets, with several hundred othervolunteers in the process of submitting one or the other. Sanders hopes topublish his findings from the first wave of DNA samples in a scientificjournal sometime next year.
Sanders cautioned a linkage study can single out only regions of thegenetic code, not individual genes.
“One of the advantages of linkage studies is that we don’t have to knowthose things ahead of time,” Sanders said. “It’s a big advantage here becausewe don’t know about the biology of sexual orientation yet, so we can find thegenes first and then study the biology.”
At this point, the researchers do not know what types of genes they mayfind; they could be related to hormones, sexual development or a completelyunexpected system.
“The genes would probably be doing their work by affecting sexualdifferentiation of the brain during prenatal life,” said J. Michael Bailey, aNorthwestern University psychology professor involved with the project. “Butwhat scientists are increasingly appreciating is that genes can affect a traitin ways you could never have guessed.”
The hunt for specific genes that affect sexual orientation may take severalyears, but the implications of this eventual finding are being fiercelydebated already.
“I think this kind of research receives a lot more criticism and attentionbecause people often think it has profound implications for social and moraldecisions,” Bailey said. “This is a controversial area. Even though itfascinates people, it scares people from the research end.”
Researchers involved with the project believe finding a genetic linkagewill help settle arguments over whether homosexuality is a choice or an innatetrait.
“A lot of times people we talk to see this research as providing evidencefor something they may [have] already had a notion for, that sexualorientation is influenced by pretty early events out of their control,” saidSanders.
Sanders also suggested that as proof of biological predisposition grows, sotoo does acceptance and tolerance of homosexuals. A Gallup poll conducted inMay indicated 42 percent of the surveyed population believe homosexuality isbiologically determined – the highest percentage witnessed in 30 years ofpolling.
Study volunteer Jason Palmer of Chicago said he hopes evidence of abiological source for homosexuality would change people’s opinions on sexualorientation.
“Our strongest opponents are the religious right, many of whom feel thatGod does not make mistakes,” Palmer said. “So if it’s a genetic factor andproven, perhaps many of them will find an acceptance for homosexuals.”
But some outside observers worry about how proof of a genetic component tohomosexuality might be used politically and even medically.
“If you do research on any human behaviors that would allow us either totreat the behavior or to prevent it altogether by prenatal testing, you havegot to ask yourself serious questions about societal context in which thistype of research takes place,” said Udo Schuklenk, a professor of philosophyat Queen’s University in Kingston, Ontario.
Critics fear identifying a biological component will lead to prenataltesting and perhaps even treatments for homosexuality. While both Sanders andBailey expressed doubt about the scientific feasibility or public demand forsuch applications, Schuklenk suggested they were not considering the worldwideimplications.
“I understand why U.S. gays want to know why gay people are gay andunderstand where they are coming from – there are legal reasons, and theagenda is progressive within the context of the U.S.,” said Schuklenk. “Whatworries me is that they show a complete disregard of repercussions of researchon the international scale, for gay people in societies where civil rights arenot as well-protected.”
Mierow said he considered the potential negative ramifications when hevolunteered for the study but trusted that changing social views onhomosexuality 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 bigotryis 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 nogood evidence that knowing things is risky; ignorance is what messes us up.”
For now, these discussions will remain largely theoretical until theresults 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 ofhomosexuality, they may also answer more general questions about gender andsexuality.
“Knowing what causes sexual orientation is important scientifically,” hesaid. “It’s an important aspect of who we are and will provide knowledge aboutthe development of gender, how men and women differ from each other.”
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 rmitchum@tribune.com