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Researcher Alan Sanders signs up Daniel Velez Rivera on Boston Common for a study using gay brothers to search for the genetic basis for homosexuality. (Illustration / Chris Buzelli; Globe Staff Photo / David Kamerman)

With imprinted genes, there is no backup engine. So if there's something atypical in the copy from mom, the copy from dad cannot be turned on. The UCLA lab is now collecting DNA from identical twins in which one twin is straight and the other is gay. Because the twins begin as genetic clones, if a gene is imprinted in one twin, it will be in the other twin as well. Normally, as the fetuses are developing, each time a cell divides, the DNA separates and makes a copy of itself, replicating all kinds of genetic information. It's a complicated but incredibly accurate process. But the coding to keep the backup engine shut down on an imprinted gene is less accurate.

So how might imprinted genes help explain why one identical twin would be straight and the other gay? Say there's an imprinted gene for attraction to females, and there's something atypical in the copy the twin brothers get from mom. As all that replicating is going on, the imprinting (to keep the copy from dad shut down) proceeds as expected in one twin, and he ends up gay. But somehow with his brother, the coding for the imprinting is lost, and rather than remain shut down, the fuel flows to fire up the backup engine from dad. And that twin turns out to be straight.

IN THE COURSE OF REPORTING THIS STORY, I EXPERIENCED A good deal of whiplash. Just when I would become swayed by the evidence supporting one discreet theory, I would stumble onto new evidence casting some doubt on it. Ultimately, I accepted this as unavoidable terrain in the hunt for the basis of sexual orientation. This is, after all, a research field built on underfunded, idiosyncratic studies that are met with full-barreled responses from opposing and well-funded advocacy groups determined to make the results from the lab hew to the scripts they've honed for the talk-show circuit.

You can't really blame the advocacy groups. The stakes are high. In the end, homosexuality remains such a divisive issue that only thoroughly tested research will get society to accept what science has to say about its origin. Critics of funding for sexual orientation research say that it isn't curing cancer, and they're right. But we devote a lot more dollars to studying other issues that aren't curing cancer and have less resonance in society.

Still, no matter how imperfect these studies are, when you put them all together and examine them closely, the message is clear: While post-birth development may well play a supporting role, the roots of homosexuality, at least in men, appear to be in place by the time a child is born. After spending years sifting through all the available data, British researchers Glenn Wilson and Qazi Rahman come to an even bolder conclusion in their forthcoming book Born Gay: The Psychobiology of Sex Orientation, in which they write: "Sexual orientation is something we are born with and not `acquired' from our social environment."

Meanwhile, the mother of twins Patrick and Thomas has done her own sifting and come to her own conclusions. She says her son's feminine behavior suggests he will grow up to be gay, and she has no problem with that. She just worries about what happens to him between now and then.

After that fateful call from Patrick's school, she says, "I knew I had to talk to my son, and I had no clue what to say." Ultimately, she told him that although he could play however he wanted at home, he couldn't tell his classmates he was a girl, because they'd think he was lying. And she told him that some older boys might be mean to him and even hit him if he continued to claim he was a girl.

Then she asked him, "Do you think that you can convince yourself that you are a boy?"

"Yes, Mom," he said. "It's going to be like when I was trying to learn to read, and then one day I opened the book and I could read."

His mother's heart sank. She could tell that he wanted more than anything to please her. "Basically, he was saying there must be a miracle - that one day I wake up and I'm a boy. That's the only way he could imagine it could happen."

In the year since that conversation, Patrick's behavior has become somewhat less feminine. His mother hopes it's just because his interests are evolving and not because he's suppressing them.

"I can now imagine him being completely straight, which I couldn't a year ago," she says. "I can imagine him being gay, which seems to be statistically most likely."

She says she's fine with either outcome, just as long as he's happy and free from harm. She takes heart in how much more accepting today's society is. "By the time my boys are 20, the world will have changed even more."

By then, there might even be enough consensus for researchers to forget about finger lengths and fruit flies and gay sheep, and move on to a new mystery.

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Original source: http://www.boston.com

 

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