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Are You My Cousin?

How DNA technology can help solve mysteries in your family tree.

I recently received an e-mail from a cousin of mine out on Long Island—we’ll call him Harry—who was writing to invite me to a family reunion. It was an offer I couldn’t resist, even though, as family reunions go, this one is a bit unusual. For one thing, Harry and I have never met. I didn’t even know he existed before he e-mailed me. In fact, though I know for certain that he and I are related, I don’t know exactly how. Neither does he. For that matter, the entire family gathering is composed of people who know we are related, but little else. The guest list isn’t set—actually, it’s growing all the time—but that’s okay, because we don’t have to rent a space, or figure out how much potato salad to make. This reunion, you see, is happening online. It’s virtual. And perpetual.

See also: What's Your Family Story?

Welcome to the astonishing, edifying, and sometimes perplexing world of tracing your roots using DNA. Just swab the inside of your cheek and you can learn some amazing and even life-changing things about yourself and your family—even if they’re not the things you were hoping to learn. You could learn that you are descended from Moses’ brother, Aaron, for instance. Or maybe Genghis Khan.

So how did I, a guy who had to wax the teacher’s car just to pass high-school biology, get into something like this? Well, I always wanted to have a large extended family. An armchair psychologist would probably tell you that this led to a longing for a sense of community, and that this in turn led to an interest in genealogy. For years I hoped that some relative would just present me with an enormous, elaborate family tree. Sadly, no one did. So I started working on one myself. I made some exciting discoveries at first, but then I had the quintessential genealogy experience—I hit a wall.

I started hearing sensational stories about DNA tests: Norwegians who discovered they were really Chinese, for example.

It’s inevitable: Everyone who sets out in search of roots will come to a point where he or she just cannot track down that next great-great-grand-somebody-or-other. My wall was the Atlantic Ocean. I was able to track down lots and lots of ancestors in America; in Europe, not so much. Those forebears’ birth, marriage, and death records may have existed once, but in the course of two world wars, the Russian Revolution, and seven decades of communism, they seem to have been misplaced.

Are You My Cousin?

Stephen Simpson/Getty Images

DNA testing could add to the number of relatives at your family reunion.

Frustrated, I posted some questions on genealogy websites, in the hope that some distant cousin might read them. No such luck. My questions are still sitting up there, sad and unanswered. But technology had other things in store. At the same time the Internet was blossoming, tremendous strides were also being made in the field of genetics. One day a man—a genealogist who had run up against his own wall—hit upon the notion of marrying the Internet with genetic science, and in doing so transformed genealogy, and the very notion of family, forever.

A few years ago, I started hearing sensational tales of people who took DNA tests and made astonishing discoveries about their backgrounds—white people who discovered black ancestors, black people who discovered Native American ancestors, Norwegians who discovered they were really Chinese, and so on. Getting nowhere online, I thought I should look into this DNA thing. So I found a testing company, sent off for a kit, swabbed the insides of my cheeks for cells, sent the samples back, and waited for the results.

That company is called Family Tree DNA; its founder, Bennett Greenspan, is the man I mentioned above, the one who first launched a commercial venture combining the Internet with genetics. Greenspan, who lives in Houston, had been a hard-core genealogist since he was a teenager in the 1960s. By the spring of 1999, though, it seemed as if he’d reached the end of the line. The problem was his mother’s mother’s father, about whom he couldn’t find much more than a surname, Nitz. “So I entered the name into a database at a genealogical website,” he says, “and found someone looking for that same name who was in Buenos Aires.” They compared notes and found striking parallels in their families. He couldn’t find a paper trail link, however. He knew they must be related—but how?

Then he got an idea. Geneticists had recently proven that some African Americans were descendants of Thomas Jefferson or a close male relative of his, and that certain Jewish men were descendants of the priestly line of the biblical Aaron. If genetic testing could help other people discover their ancestry, Greenspan thought, “Why not me?”

He tracked down Michael Hammer, Ph.D., at the University of Arizona, one of the geneticists whose work had been in the news. All Greenspan wanted to do was pay to submit a sample of his DNA. But Hammer wasn’t interested. “Someone should start a company doing this kind of testing,” the doctor sighed. “I get calls from crazy genealogists like you all the time.”

And that, Greenspan says, “was a true eureka moment.” He sat down, wrote a business plan, and within months launched Family Tree DNA, the first company to offer the general public the opportunity to use genetic science in the pursuit of genealogy. And he enlisted, as his chief scientist, Michael Hammer.

To understand how all this works, it helps to know that almost all of the genetic material you inherit from your parents is thoroughly mixed together, and is thus unique to you. It can be used to link you to living relatives, but it can’t tell you much about your ancestors.

There are two intriguing exceptions, though—and, so far, they form the whole basis of genetic genealogy. One is something called mitochondrial DNA (mtDNA), which a mother passes on to all of her children. If you’re a woman, you have that. If you’re a man, you also have your father’s Y-chromosome, which is passed down, intact, from father to son to son. (For more details, see “Under the Microscope,” below.)

Because these two genetic elements remain virtually unchanged generation after generation, they create two clear, if narrow, trails you can follow back through time—the line of your mother’s mother’s mother and so on, and the line of your father’s father’s father and so on. Because these genes don’t come bearing microscopic labels that read “Senegalese” or “Mongolian” or “Dutch”—let alone “Grandma Gertrude” or “Great-grandpa Fred”—the only way to determine anything about your ancestry based upon your DNA is to find your genetic matches and then compare your paper (or digital) family tree with theirs. Because you and your matches share a common ancestor, their research could fill gaps in your own—and vice versa. Most genetic genealogy companies will put you in touch with your genetic matches, but the rest is up to you. “What I tell people,” says James Freed, Ph.D., an avid genealogist and retired professor of zoology who taught genetics, “is that you have to have a hypothesis about your family beforehand.”

Fortunately for me, I had one. In fact, I had more than just a hypothesis. I actually knew where my ancestors had come from in the 19th century. Still, when I first received my DNA test results, I found the data confusing. I liken it to walking into an antiques shop with the lights off: you know the place is full of fascinating stuff, but you have to wait a bit, until your eyes get adjusted to the darkness, to find out exactly what’s there.

The more obvious discoveries will reveal themselves first. For instance, in comparing myself with my matches, it quickly became apparent that I am of Jewish descent—something I had suspected at least since my bar mitzvah. I also wasn’t too surprised to learn that my matches’ ancestors were mostly, like mine, from eastern Europe. But eastern Europe is a big place; while I had believed that my maternal line originated in Lithuania, I found close matches in western Poland, Romania, the Czech Republic, and eastern Ukraine. Even more dispersed is the family on my father’s side: while my earliest known ancestor in that line came from Belarus, I found close matches in such distant locales as Germany, Latvia, Hungary, and Bosnia. Oh, and also Puerto Rico, where the family of a man I’m supposedly related to has been living for more than 300 years.

Now that was a head scratcher. At first I thought it must be a mistake. But we are, indeed, a match. There is a 96.56 percent chance we share a common ancestor within the past 24 generations. That’s about 600 years ago—or some 85 years before all Jews were expelled from Spain. Which means there’s a good chance I’m not only eastern European but Spanish.

That revelation, though, wasn’t as big a surprise as the e-mail I received just a day after I first saw my results. It was from Harry, the cousin I mentioned earlier. You see, when you swab the inside of your cheek, you also give your name and e-mail address, and indicate whether you wish to share them with others. If you do, you and your genetic matches will be able to contact one another. This function is what really makes the process worthwhile, because it enables two previously unacquainted people to work together on tracing their shared family tree. (The image that comes to my mind is of two miners tunneling toward each other in the hope they’ll eventually meet.)

This, says Bennett Greenspan, was his vision from the start. Today his company’s database has more than 200,000 people in it. Greenspan configured that database so it would seek out matches between members and facilitate their getting in touch with one another. Which means that every time a new person enters the database, matches are instantly notified of the newcomer’s arrival.

So back to my e-mail from Harry. He was writing, he explained, to invite me to join a club of sorts, in which all the members were genetically matched. Not to brag, but my cluster group has 81 members at present and is, according to Greenspan, one of the largest and most active. I, of course, couldn’t be prouder.

But here, at last, is perhaps the most surprising thing of all: what seems, on the surface, to be the coldest, most impersonal means of tracing your own lineage is anything but. As I have said, before I received that e-mail, I had no idea Harry existed. Aside from the fact that he and I both live in the New York City area and share a direct ancestor, we have very little in common. He’s in his 80s, was born in Vienna, and is an electrical engineer; I’m in my 40s, was born in New York City, and am still inclined to stick a fork in the toaster unless someone stops me. And yet we have become very friendly, talk and e-mail often, and have even made plans to visit in person.

It’s strange to think that it wasn’t some outside networking entity but something deep inside me—not the Elks lodge or MySpace but my own DNA—that managed to offer me such a strong sense of community. I’ll have to find an armchair psychologist to tell. I’m sure there must be one in the family.

Richard Rubin wrote about collecting in the March & April 2008 issue.