"It's a very different way of thinking about life, really," says Jirtle. Francis still remembers the chilly reactions she received the first time she presented a poster at a scientific conference. More than one geneticist, she says, walked away upset. A colleague in integrative biology who works closely with Francis gives similar accounts.

With the successful sequencing of the human genome, the news in recent years has been filled with reports about the isolation of genes said to "cause" everything from diabetes to voter turnout. DNA has run wild in the popular lexicon, to the point that fashion execs now blithely talk about "consumer DNA," and the culinarily proficient are said to have "breakfast in their genes." Such usage hints at something larger; namely, that in the question of nature versus nurture, we've embraced the view that our fates are written in genetic code. But increasingly, researchers are finding that genes don't tell the whole story.

Asthma is one of those diseases that has been explained over the past century as the product of an excitable nervous system, poor mothering, too little dirt in the household ... or, in recent years, genetic destiny. Just last fall, when scientists pinpointed a gene they believe raises asthma risk by as much as 60 percent, journalists proclaimed the triumph of genes over environment. But John Balmes, a pulmonary physician who directs the Center for Occupational and Environmental Health at UCSF, favors a more complicated picture.

Balmes compared Berkeley freshmen from the Bay Area to those who grew up in Los Angeles. Students from the smog-ridden south, he found, had the narrow airways that typify chronic lung injury. But the extent of the damage differed according to two very common gene variants. Asthma, Balmes expects, will pattern similarly, with pollution interacting with genes to worsen the allergic response that triggers asthma attacks. "Environmental factors," he concludes, "can affect genetic responses, and genes can affect responses to the environment."

Francis would no doubt agree with Balmes. Her work has been among the first to show, in fact, that epigenetic influences go far beyond the common conception of "environment" to include things such as social interactions. With that in mind, her lab collaborates with scientists across the spectrum: in molecular biology, the School of Public Health, psychology, and even moral reasoning. The links may strike some hardcore geneticists as alien territory, but with findings like Francis's, these doubters too may soon find themselves arm-in-arm with the "soft" sciences. Darlene Francis considers herself a member of both camps. "I'm a Ph.D. in neuroscience, but at heart a social worker," she says.

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