Some 25 million people have watched his shows on public television about tracing ancestry. But Gates isn't satisfied with folks simply turning on the TV. "We cannot fully tell our collective history in as much detail as I hope it will one day be told until a huge percentage of the African-American community does its family tree and has its DNA tested," he said.

Already, there has been a significant uptick in interest, with 3,000 people ordering kits through the Roots Into the Future project so far. "We are really excited by the positive response," Mountain said. "It's been wonderful."

Of dozens of 23andMe health surveys, three are the highest priority for the project, Mountain said. One, general health, focuses on conditions that are common among African Americans, while a second survey covers allergies and asthma, and a third homes in on headaches and migraines.

Researchers compare people who have the health condition of interest with those who are healthy, searching for places in their genomes where there is a difference. The 23andMe genotyping chip looks at a million SNPs, or single nucleotide polymorphisms, permitting the researchers to study hundreds of health conditions simultaneously.

(An SNP is the most common form of genetic variation among people; each one represents a difference in a nucleotide, a single DNA building block. While most SNPs have no effect on health, according to the National Institutes of Health, some SNPs act as markers, pointing to genes associated with disease, and some play a more direct role in disease by affecting a gene's function.)

Targeting Black Americans' Health

The first goal of 23andMe is to validate genetic markers -- which have been identified in other ethnic groups -- that have an influence on disease risk.

"In African Americans, no one has tested it," Mountain said, referring to validation of the markers. "No one knows if it holds up."

The next goal is to identify new genetic markers for African Americans for pressing diseases, such as diabetes, prostate cancer and heart disease.

The company promises to share all of the data with the participants, thus "empowering consumers," said Anne Wojcicki, 23andMe co-founder and chief executive. One of her "pet peeves" with the traditional research model is that it doesn't give such critical information to participants.

In addition to providing genetic risk factors for various diseases and health conditions, the free service offers Web-based tools to find and connect with living relatives through their matching DNA. Wojcicki said it's "tragic" that some communities are underrepresented in genetics research, since the research has the potential to improve everyone's odds of having healthier lives. It's a lesson she learned personally.

The 23andMe results for Wojcicki and her husband, Google co-founder Sergey Brin, prompted the couple to make changes to help improve their health. Because of the risk for macular degeneration, a leading cause of vision loss in Americans 60 and older, Wojcicki gives her extended family sunglasses as birthday and holiday gifts. And her higher risk for breast cancer led her to cut out social drinking, since alcohol consumption has been cited as a risk factor in some cancers. She said that her husband's heightened risk for Parkinson's disease, a neurological disorder that affects nerve cells in a part of the brain that controls muscle movement, was a motivating factor for Brin's weight loss.

"It's definitely had a big impact," she said.

For more information about Roots Into the Future, go to 23andme.com/roots/.

UPDATE: Because of regulations, sample collection kits can be shipped to New York, but sample collection and return shipping must take place outside of the state of New York; kits cannot be shipped to or from Maryland.

Diedtra Henderson is a freelance science and technology writer.

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