Even the most diligent researcher may not find answers in the genes given the current technology. The first company Edward Ball used to test his DNA told him he was 13 percent American Indian. That was a surprise; in researching his 1998 book, Slaves in the Family, Ball, who is white, found evidence that he's related to African-American descendants of his forebears' slaves. Yet tests by two other genetic genealogy companies discounted the American Indian link. After further testing of his DNA and that of relatives, living and dead, through multiple companies and university researchers, Ball still doesn't have a clear sense of his genetic roots. "Most of us look at DNA as a sacred substance that has the deepest truths about human life," says Ball, who recounts the quest in his new book, The Genetic Strand. "The reality is, there are many ambiguities."
Raising the ante. Much has been made of the privacy risks posed by social networking sites like Facebook and MySpace. The new gene-testing sites raise the ante by encouraging customers to upload family trees, or even family medical histories. That information makes the data more useful for medical research—and also more potentially damning. A bill to protect people from discrimination by insurers and employers based on genetic information is stalled in Congress, and private DNA databases don't fall under the medical-records privacy provisions of state and federal law. There's nothing to keep a company from, say, selling the database as an asset if it goes bankrupt.
Church argues that since it's impossible to guarantee privacy, it's better to let it all hang out. (He has posted his health problems, which include heart attack, narcolepsy, and dyslexia, on his website with the wry aside, "Insurance companies take note.") His Personal Genome Project will ask participants to take an entrance exam showing that they understand the privacy risks posed for themselves and relatives. When one person posts DNA online, for instance, it reveals 50 percent of the genetic variation in the person's parents and children. "I encourage the first family member to check it out with the rest of the family before they do anything public with their data," Church says.
Even good tidings from our genes must be taken with a grain of salt. Stefánsson's risk of Alzheimer's, as calculated by the decodeme site, is 49 percent lower than that of other men of European ancestry. That result comes from calculations on the risk posed by variations in a gene, APOE, that studies have associated with Alzheimer's. But the APOE variant is just one factor. Others are age, cardiovascular disease—and chance. Understanding of how those factors relate is imperfect at best. Yet uncertainty, he says, is no reason not to see genetic scans as a useful tool. "There are a lot of people out there who just want to learn more about themselves."