SCIENCE

Blue Blood, Black Genes

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By Reviewed by Susan Okie
Sunday, November 25, 2007

THE GENETIC STRAND

Exploring a Family History Through DNA

By Edward Ball

Simon & Schuster. 265 pp. $25

Several years ago, Edward Ball took possession of an ancient family desk and discovered something in a locked compartment that to him must have seemed almost predestined. He found a collection of carefully labeled and dated locks of hair from nine of his 19th-century relatives, the oldest specimen dating from 1824. Ball was uniquely qualified to explore the implications of such a trove: His 1998 book Slaves in the Family was a National Book Award-winning investigation into his white ancestors' dealings with their African slaves. Now he held in his hands the means to take that exploration a giant step further. Perhaps modern DNA analysis of his ancestors' hair could provide evidence of unsuspected liaisons, redraw the tree of genetic relationships, and deepen Ball's understanding of his family's story and his own identity.

The Genetic Strand is the tale of Ball's efforts to extract truth from these preserved hair specimens, and of what he learned about the power and pitfalls of DNA testing as a tool for exploring ancestry. The book engagingly switches back and forth between history and science, alternating anecdotes from the lives of the family members with visits to the labs of the various biologists who assist Ball with his genetic quest. Ball is not a science journalist, but in this case that's not a deficit: An elegant writer and a consummate researcher, he navigates through complicated subjects like DNA fingerprinting and the use of mitochondrial DNA to trace female lineages without resorting to what he disparagingly calls "The Vocabulary" of molecular genetics. Clarity and deft use of analogies help him deliver good enough scientific explanations to move the story seamlessly along.

Disappointingly (though not surprisingly), some samples yield no genetic material, but others do unlock information -- and the suspense mounts. Does the Balls' purportedly white, northern European family tree contain sprigs from two other continents, as certain test results suggest? Was Ball's great-grandmother, the striking Kate Fuller, part African? Do genes explain the tragic mental illness of a great-grandfather who spent much of his life locked in an attic, and whose daughter was similarly afflicted? Do high lead levels in hair samples mean that some of the Balls suffered from lead poisoning, perhaps caused by lead-lined water pipes in the family mansion or by the glaze on their Wedgwood china?

Ball's longing to know the answers stems, in part, from a wish to puncture the hypocrisy and racist pride of socially prominent Southern families whose members married their cousins, increasing their chances of passing on hereditary diseases caused by recessive genes, rather than risk a match that might be judged unsuitable. He enlists a couple of his own cousins, fellow iconoclasts who enthusiastically provide samples of their DNA to aid his investigation; other relatives are horrified by the possibilities he's raising. As Nobel prize winner Kary Mullis (another iconoclast, though not a relative of Ball's) warns him, "DNA causes strange responses in people, all sorts of irrational reactions."

Ball meets with scientists who trace the history of mass human migrations, run giant commercial labs that perform paternity tests, offer DNA-testing for African Americans curious about the geographic origins of their forebears, or study markers on the Y chromosome to try to determine whether Thomas Jefferson fathered children by his slave, Sally Hemings. He measures the gap between people's fantasies about what genetic testing can reveal -- expectations often inflated by corporate claims and rosy media coverage -- and the reality that such test results are subject to error and uncertainty. "Without trying to do so, molecular biology offers several elements of religion," Ball observes. "It possesses a strong story of origins (evolution); it deals in a sacred substance (DNA); and it has a touch of the ineffable (the enigmatic 'molecule of life')."

Anyone intrigued by family history will find The Genetic Strand an engaging yarn and will come away with a more nuanced understanding of the complexity of each individual's genetic past. As biologist Rick Kittles, scientific director of a lab called African Ancestry, tells Ball, "When you go back 350 years, let's say ten generations ago, you have about 14,000 ancestors. You can't tell everything about them. What we can do, with good confidence, is tell you something about your mother's mother's mother's mother, or your father's father's father's father." To many people longing to know more about their family's past, any clue to a great-great-grandparent's probable region of origin would be a treasure; to others, it might seem a meager payoff for the expensive, high-tech scrutiny of genes. ¿

Susan Okie, a physician and contributing editor at the New England Journal of Medicine, is the author of "Fed Up! Winning the War Against Childhood Obesity."


© 2007 The Washington Post Company

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