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I was a junkie stockbroker
How one trader learned that there's more to life than the vicissitudes of the market.
By Bolt Edsall
[06/24/99]

Under my skin
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By Jon Bowen
[06/23/99]

Urge
Toeing the line
Ambition and her toe lingered between us on the couch that day.
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[06/22/99]

Curing with compassion
Beth Israel Hospital in New York brings in the Dalai Lama to dedicate a new space.
By Alyson Mead
[06/21/99]

Urge
Girl fight, boy fight
Is barroom brawling good romantic bonding?
By Lily Burana
[06/19/99]

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By Arthur Allen

June 25, 1999 | In 1993, a National Cancer Institute researcher named Dean Hamer made what seemed to be an astonishing discovery about the genetics of human behavior. He had located a link to male homosexuality on the X chromosome, Hamer reported in Science. The story was splashed across front pages around the country. At last, overly doting mothers and early cross-dressing games were off the hook and the predilections of everyone from Walt Whitman to Liberace could be explained by a few errant proteins. Hamer's article, based on an examination of the DNA of 40 gay brothers, led to mass-market book deals and minor celebrity. There is only one small, underreported glitch: Hamer's results have never been replicated. Two subsequent studies showed much weaker evidence of a gay gene; a third, published April 23 but overshadowed by the massacre at Littleton the day before, found no evidence at all. "There is no hint or trend in the direction of the initial observation," George Ebers, a Canadian investigator involved in the study, said in Science.

A quick trawl through the headlines of the 1990s finds a similar fate for other front-page genetic breakthroughs. Despite much-publicized discoveries of genes for schizophrenia, manic-depression, alcoholism and bipolar disorder, the precise genetic components of these illnesses continue to elude science. The same goes for personality traits. The much-trumpeted discovery of a "novelty-seeking gene" in 1996 hasn't been replicated -- nor have various "depression genes." This is not to say that progress isn't being made in parsing the biological components of behavior. But in any given person, the interplay of genes and the environment is a horrendously complex story. Individual genes produce quite subtle effects, and the more we learn about DNA, the clearer it is that any particular gene's potential can be shut down or enhanced by complex biochemical pathways contingent upon things like sleep, nutrition and stress.

To find out more about genetics, click here.

A decade ago the field of behavior genetics was aflutter with the hope that molecular biology would home in on what makes each of us tick. But "the fog is lifting very slowly," says Kenneth Kendler, a professor of psychiatric genetics at Virginia Commonwealth University in Richmond. "We've learned that in psychiatric disorders, there are no single genes of really large effect. If there were, we'd have found them already." Genes for certain conditions, such as Huntington's or sickle cell disease, are known as simple Mendelian traits because they follow the straightforward model of inheritance noted by the Austrian monk Gregor Mendel last century. "Mendelian traits are like a trumpet call. The genetic signal blasts right through," says Kendler. "But the genetic effects in [most behavioral disorders and traits] are like whispers in a busy train station. It's hard to distinguish them from the background noise."

That behavior is a tricky business to predict was elegantly demonstrated by another study published in Science this month. A group of researchers at three universities -- in Oregon, upstate New York and Edmonton, Alberta -- ran a set of identical experiments on eight different mouse strains, each bred to show distinct behavioral attributes. The idea was to see whether they would act according to type. They didn't. In some tests, genetically identical mice acted differently depending on the lab that tested them. A strain of mice lacking a receptor for the neurotransmitter serotonin -- a substance whose imbalance has been implicated in various addictions and mood disorders -- was expected to drink more alcohol and show more anxiety than the other mice strains. But all three teams found that the serotonin-mutants didn't booze it up any more than the others. And all strains of mice tested in Alberta, it turned out, were mellower than the New York and Oregon mice. Must be the weather, eh?

Next page | Twins with identical genes have brains that look different