Mixed roots: Science looks at family trees

After his parents died, Malcolm Dodd began to suspect he wasn't his father's son. A relative came forward with a story, and the pieces seemed to fit. His father had spent three years fighting in Southeast Asia during World War II, when Mr. Dodd was born. Some sleuthing led him to suspect that his biological father might have been an American soldier stationed in Britain. But Dodd - born and raised in Britain and now retired in Portugal - wanted stronger evidence.

That's when he turned to DNAPrint Genomics Inc., in Sarasota, Fla. He sent the company a cotton swab he had brushed along the inside of his cheek to collect some of his DNA. What he got back wasn't ironclad proof. If anything, it was even more surprising: Some of his ancestors were likely to have been native Americans.

"I expected I would be 100 percent European," Dodd says. The result added to his conviction that his father was an American, and since then he's visited California to follow more leads. "I've got a shrewd idea as to who my father was," he says, although they can't be reunited, since the man died long ago. The DNA test "was a great help," says Dodd, who says he loved the father who raised him as his own and bears no ill will to anyone involved.

Among the many spinoffs from the 2003 completion of the Human Genome Project - a government-funded effort to sequence and map all the human genes - is a new ancestry industry. Companies are using DNA markers passed from generation to generation to let people peer into the past to learn their genetic roots. The DNA data, rarely conclusive on their own, need proper interpretation to be understood fully. And while the for-profit nature of such research raises ethical issues for some, the availability of such tools is proving alluring for many.

In the United States, for example, some people are eager to prove they have native American ancestry in order to join a tribe, many of which are growing wealthy from casino revenues. Others are fascinated to learn of hitherto unknown ties to the past. But in a country where "one drop" of ancestral African blood once meant the risk of enslavement, news of DNA origins can come as a shock.

The bottom line: We're not as racially pure as we think we are.

An African-American, for example, on average will find that he or she has about 20 percent European ancestry, says Tony Frudakis, founder and chief scientific officer of DNAPrint.

Last fall, Samuel Richards, who teaches a race-relations course at Penn State University, arranged for 100 of his students to take the DNA test. About 20 percent were "very surprised" to find out they had a mixed heritage, he says, and about 20 percent more were somewhat surprised. The DNA test helped the students "see outside the race box," Professor Richards says. "We generally think that there are these set and well-demarcated boxes, when race is, in fact, really very fluid and changing."Next year, Professor Richards plans to offer the DNA test to 1,000 of his students.

Sometimes, the tests raise more questions than answers. Richards's wife, Laurie, who also took the test, found that her ancestry was 13 percent native American, 87 percent European. That was odd because she traced her ancestors back to Poland and Ireland and had no knowledge of any native Americans in the family tree. It led her to interview older relatives to try to solve the mystery.

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