Putting the Gene in Genealogy

It’s in your genes: That’s often how we explain away physical and personality characteristics. Genes hold a lot more information, however, than why you get freckles or can swing a baseball bat better than anyone else on the team. Using new scientific discoveries, genes may enable you to trace your family tree back not merely a few generations but hundreds, even thousands of years.

That’s how Bryan Sykes, a human genetics professor at Oxford University in England, recently traced his lineage back more than 600 years. Using the Y-chromosome of his DNA and that of 250 other men with the surname Sykes, he discovered that almost all share one founding male—the original Mr. Sykes, who lived sometime in the 14th century, when surnames first came into use in England.

Geneticists use Y-chromosomes to trace paternal ancestry because fathers pass their Y on to sons virtually unchanged. Each man’s Y is, in a sense, a genetic connection to his forefathers. Through his research, Sykes realized he could trace many surnames back to an original male founder using the same process. But DNA reveals more than just name origins, scientists at Emory and Stanford universities have found. It also leads us back to our ancient roots, when Homo sapiens emerged hundreds of thousands of years ago. Only about 2,000 humans made up that original population, and of those, only one woman’s and one man’s lineage survived through the ages. That woman (“Eve”) and man (“Adam”) lived in Africa about 144,000 years ago, when the population began to disperse across the globe. As early humans migrated, small changes in their DNA occurred, depending on when and where they lived. The genetic record of these mutations can tell scientists today whether your maternal ancestor lived, for example, in Africa 140,000 years ago or in South America 20,000 years ago.

Sometimes, the irrefutable evidence of DNA stirs up sensitive issues and age-old controversies, such as the discovery that Thomas Jefferson’s Y-chromosomes match those of descendants of his slave, Sally Hemings. Now the Monticello Association, a group of 700 all-white Jefferson descendants, must grapple with the notion of accepting their ancestor’s slave’s children as relatives. So far, they have not accepted the Hemings descendants because of disagreements among the group’s members. Meanwhile, another claim of presidential ancestry comes from the descendants of West Ford, believed to be the child of one of George Washington’s slaves. The descendants are pleading their case that the first president is their ancestor, but have not yet offered up the conclusive DNA evidence that the Hemings contingent has.

DNA evidence sometimes vindicates, as it did for the Lemba tribe of southern Africa, which was found to be genetically tied to an ancient Jewish population—the same story that the tribe had passed down for a thousand years. University of London scholar Tudor Parfitt was intrigued by the tales he heard from this tribe. They told Parfitt their people were Jews who came to Africa a thousand years ago from a place called Sena. Not only did Parfitt find this “lost city,” but he also found that many of the Lemba men carry the same DNA characteristic of Jewish priests supposedly descended from Aaron. See PBS’ “Nova” Web site or a feature on Parfitt’s discovery and the other “Lost Tribes of Israel.”

Other DNA studies have found that Jewish populations across the globe have retained their biological identity despite thousands of years of Diaspora—living among other, genetically different populations. A study by University of Arizona researchers says Jews may share a common ancestral population with Middle Eastern peoples such as Palestinians, Syrians and Lebanese.

DNA researchers at Howard University, meanwhile, have opened the doors to pre-slavery ancestry information for millions of African-Americans. For $200 to $300, this genetic test can reveal what part of Africa a person’s ancestors came from. For more information, see africanancestry.com.

Not everyone is happy about the recent explosion of genetic research. Critics in Newfoundland are calling for government regulation of such research. Because 90 percent of Newfoundlanders descend from a population of 20,000 to 30,000, genes there have fewer mutations and are better for DNA studies. As scientists flock there, the province wants to ensure its residents are not poked and prodded by outside researchers without some benefit to the province’s citizens. The government, therefore, is establishing an ethics board to review all genetics research done on the island and developing research standards for future studies. A similar controversy has erupted over deCODE Genetics’ plans to create a database of all known Icelanders for the history of that isolated island.

(Genetics and genealogy also mix in the increasingly important area of family health history. To see why this should matter to you and to get started tracing your own family health history, see our nine steps to a family health history.) 

You don’t have to be a geneticist to find out what your DNA says about your ancient forebears. Oxford Ancestors, a company recently started by Oxford’s Sykes, will analyze your DNA for all kinds of information: which “daughter of Eve” you come from (including where and when she lived); the current geographic distribution of your surname (only in mainland Britain); and whether males with the same surname are related. Costs range from $50 to $180 for single tests, which involve submitting a cheek swab sample.