DNA: too much information? As scientists unravel the mysteries of DNA, concerns arise about its potential misuse.

• Author: Harmon, Amy

When scientists first decoded the human genome in 2000, they portrayed it as proof of humankind s remarkable similarity.. The DNA of any two people, they said, is at least 99 percent identical.

Now, however, researchers are exploring the remaining 1 percent to explain differences among people of different continental origins--and that's proving to be a lot trickier.

For example, scientists have recently identified small differences in DNA that account for the pale skin of Europeans, the tendency of Asians to sweat less, and West Africans' resistance to certain diseases.

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At the same time, genetic information is slipping out of the lab and into everyday life: Ancestry tests tell people what percentage of their genes are from Asia, Europe, Africa, and the Americas. The heart-disease drug BiDil is marketed only to African-Americans, who seem genetically predisposed to respond to it; Jews are offered prenatal tests for genetic disorders rarely found in other ethnic groups. In the courts, DNA evidence has resulted in the exoneration of more than 200 wrongly convicted inmates.

But while these early benefits of the genetic revolution are undeniable, some critics fear this new genetic knowledge may also be giving long-discredited racial prejudices a new potency.

The notion that race is more than skin-deep could undermine principles of equal treatment and opportunity that have relied on the presumption that we are all fundamentally equal.

"We are living through an era of the ascendance of biology, and we have to be very careful," says Henry Louis Gates Jr., director of the W. E. B. Du Bois Institute for African and African American Research at Harvard University. "We will all be walking a fine line between using biology and allowing it to be abused."

Certain superficial traits like skin pigmentation have long been presumed to be genetic. But the ability to pinpoint their DNA source makes the link between genes and race more palpable. On mainstream blogs and in college classrooms, the topic is prompting questions of whether more profound differences may also be attributed to DNA.

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UNEASINESS

Scientists say that studying these differences is crucial to mapping the genetic basis for disease, but concerns remain. Renata McGriff, 52, a health care consultant in New York who had been encouraging black clients to volunteer genetic information to scientists, says she and other blacks have lately been discussing...