Arts, Culture & Media

Roots 2.0: Using DNA to Trace My Ancestry

In any family, there is always one person who is interested in genealogy — and in my family, I've always been that person.

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I'm not sure what got me interested in my family's past. Maybe it was the 1977 blockbuster TV series "Roots," which chronicled Alex Haley's search for his African forebears. I was ten years old at the time and can still remember bits of it — especially Haley's iconic exclamation, "Kunta Kinte, I have found you!" when he finally tracks down vital information about his ancestor, Kunta Kinte.

Whatever prompted my interest in genealogy, by the time I was eleven I was ardently filling in the pages of "Digging for My Roots," a book for kids that encouraged me to interview my relatives and record as much information from them as I could gather. So, armed with my blue Panasonic tape recorder, I conducted my very first interview — with my grandmother, Ray Zall, who graciously answered all of my detailed questions about her childhood in Belarus.
"Tell Me About Your Life"

The recording of my grandmother, which I still have, begins rather grandly: "This is Carol Zall interviewing Ray Zall, my grandmother, or 'Bobe' in Yiddish." It was the first of several recordings I have made with relatives — and it's both poignant and amusing.

Now, Mrs. Zall," I begin in my best radio interviewer manner, "could you tell us about your childhood?"
"What can I tell you?" my grandmother asks in her heavily accented English.
"Tell me about your life. Where were you born?"
"I was born in a small place, the name was called Kashuki."
"What?"
"Kashuki. Kashuki, it's a country, a small place."
"What country was it near?"
"That was Russian-Poland, Russian-Poland."

As you can tell from this exchange, the location of my grandmother's village was confusing to me in 1978, and it's still confusing now. She was born at the beginning of the twentieth century in what is now Belarus, but was then Poland — or, as she put it, "Russian-Poland" — and I've never been able to find her village, Kashuki, on a map. (If anyone can help me with that, please let me know). Many of my other ancestors came from similarly vague places, located in countries that no longer exist, like Austria-Hungary. I don't even know the names of the villages they came from, and that's made it hard to trace my roots.

A New Way To Trace My Family Tree

Thirty-four years after that recording was made, there are now new ways to trace my family tree. Advances in the field of genomics have made it possible to use a person's DNA to find out where their ancestors may have come from. Recently, this kind of analysis has become available — and more importantly, affordable — to the general public, and I've wanted to try it ever since I heard about it.

For about two hundred dollars, I signed up with a company called 23andMe (the name derives from the fact that we all have 23 pairs of chromosomes) — and the next thing I knew, I was spitting into a plastic tube and mailing my saliva to them.

Joanna Mountain, senior director of Research at 23andMe, explained the testing process once the saliva samples arrive at their partner lab. The first step, she says, "is to extract the DNA from the saliva. And then they take that DNA and it gets cut up into little pieces and they put the DNA onto what we call a chip, or a genotyping array."

Three Billion Letters

Human DNA is like a code, made up of three billion letters. 23andMe doesn't look at all of those letters, or "positions," as they're called; they just look at about a million of them. Looking at that subset is what is called "genotyping".

According to Mountain, the genotyping chip, or array, has lots of little strings of DNA on it. 23andMe looks to see which of the strands of DNA on the chip match the strands of the DNA of the customer, and that tells them which variants the customer has at various positions on their genome.

"Those positions are chosen because they are particularly interesting," says Mountain, "because they vary from one person to another."

It's those interesting positions that testing companies like 23andMe are using to find out all kinds of information — everything from diseases you could be at risk for in the future, to details about your past.

How It Works

Although the medical side of DNA testing is fascinating — and is going to change the way medicine is practiced — I was most interested in what DNA testing could tell me about my past. Testing companies like 23andMe have a few different kinds of genetic information they can look at in order to learn about a person's ancestry. First, there's the Y chromosome. It's something only men have, and since a man has only one Y chromosome, it gets passed down from father to son without changing or combining with any other genetic material.

Bennett Greenspan is the President of Family Tree DNA, another company that offers a genotyping service direct to the public. He told me that by looking at the Y chromosome, we can get a perfect picture of a person's "father's father's father's father's line, just by testing one male from that particular lineage."

"We can tell an individual that their father's father's father's direct male line is native American or sub-Saharan African," says Greenspan, "even if they think of themselves after looking in the mirror, as a Caucasian individual."

That kind of surprising discovery is possible because the male ancestor revealed by a man's Y chromosome is only one of the many ancestors whose genes he carries. So a person could have mostly European DNA, and look European, even if his Y chromosome traced back to an African forebear.

Just as with the paternal line, it's possible to trace the maternal line, by looking at a certain kind of DNA called mitochondrial DNA. Mitochondrial DNA is a special piece of DNA that's passed down from mother to child, so it's used to trace the maternal line back to a common female ancestor.

In addition to the X and Y chromosomes and a person's mitochondrial DNA, there's also the DNA from the other 22 pairs of chromosomes. This DNA represents genes from all the other ancestors you've ever had, not just your direct paternal and maternal lines, and is called "autosomal DNA".

New Ways to Find Cousins

Autosomal DNA recombines in every generation — and it's this "re-shuffled" autosomal DNA that companies like Family Tree DNA and 23andMe are using to try to squeeze out as much ancestry information as possible. While the testing companies don't provide the kind of information you'd get from traditional genealogical research, they do have searchable databases that allow customers to look for and contact people who share identical gene segments — potential genetic cousins who may be able to pool records and other information about known common ancestors.

"Of course this is of great interest to genealogists," says Blaine Bettinger, editor of the Journal of Genetic Genealogy. "We're always looking for new ways to identify cousins."

Bettinger, who is a practicing attorney and also has a Ph.D. in molecular biology, says that his own DNA results helped him to fill in the blanks on his family tree.

"I have, on my maternal line, a brick wall that goes back to about 1820s in the Honduras," he explains. "And I have previously been completely unable to explore that line at all, due to the lack of records and access to records." Despite the lack of records, Bettinger was able to find a new lead — from his DNA analysis. It showed that his mitochondrial DNA (his mother's line) traced back to the Native American population.

"So although I didn't obtain any names, or dates, or anything along those lines, I was able to peek beyond this brick wall that I have."

Bettinger also got useful information from his autosomal DNA, which showed that he had both native American and African DNA — something he didn't expect from his paper trail alone.

A Boring Genome

While Blaine Bettinger made the kind of discoveries that motivate people to get their DNA analyzed in the first place, not everyone gets such interesting results.

"I discovered that I had just about the most boring genome that a person can have," says Daniel MacArthur, a research geneticist at Massachusetts General Hospital. "I discovered that I'm of European origin, which is something I already knew. I discovered that I have blue eyes, which is also true. And I haven't really found anything that really blew me away."

Despite his boring genome, MacArthur is a big advocate of direct-to-consumer genetic testing services (you can read his blog post about how to choose a reputable genetic testing service). He's one of about a dozen people — all scientists or experts in genomics — who've made their genetic data available to the public, on a website called Genomes Unzipped.

The folks at Genomes Unzipped blog about the different genomic testing services, and about the scientific, legal and ethical issues surrounding genetic testing. One of the people there, Joe Pickrell, a postdoctoral researcher in human population genetics at Harvard Medical School, did get a surprise when he put his information online.

A Not-So-Boring Genome

"I didn't know a whole lot about my ancestry, but I knew vague details," says Pickrell. "And so what happened is, actually the first day we put this data online, there's a guy who runs a website where he does ancestry analysis. And so he took all of our data and put it through his software."

Pickrell had always thought his ancestors came from Ireland, Italy and the UK. But now, there was something new in the mix: "It turned out in his analysis that I had some Jewish ancestry."

Pickrell was skeptical. "I had never heard anything about Jewish ancestry in my family and had no idea that that was even a possibility." However, he started running his own analyses — and the closer he looked, the more it seemed he did have Jewish roots. So he asked his family what they knew, and it turned out that the DNA analysis was right: Pickrell had a great grandfather who was Jewish. The great-grandfather had immigrated to the U.S. from Poland and married a Catholic woman. Worried about discrimation, Pickrell's great grandparents had decided to keep the Jewish ancestry secret. "They just said that he was Irish," says Pickrell with a laugh.

Joe's experience with genetic testing was a dramatic one (for more on his story, see his post at Genomes Unzipped) — and it was just about the opposite of my own. While he was surprised to find Jewish ancestry, I've always known that my family was Jewish. My entire family tree — as far as I know — consists of European Jews, also known as Ashkenazi Jews. So, I've always imagined my ancestors as people who spoke Yiddish, lived in Eastern Europe and listened to Klezmer music.

A Very Ashkenazi Genome

However, since Ashkenazi Jews spent centuries wandering around Europe, living among different populations, I've always wondered who else was in my family tree. After all, my mother's mother and all her siblings had red hair and blue eyes, and my own sister — a redhead with freckles — is always asked whether she's Irish. So could I possibly have Celtic forebears? As someone who went to Scotland for a year to study Celtic literature and stayed for over a decade, I have to say that I would be both astounded and delighted to find that the red hair in our family traces back to the Celts. It would be equally intriguing to find out that I had genes from some other European population.

In theory, I could have such ancestry — but what actually showed up in my DNA analysis was a very Ashkenazi-Jewish looking genome. Joanna Mountain of 23andMe went over my results with me. According to her, about two thirds of my genome "traced back to Ashkenazi Jewish ancestry either in Russia, Poland, Belarus," and other nearby countries.

The results confirmed the stories I'd heard from my relatives, showing DNA that traces to the eastern and central European countries my ancestors reportedly came from. Joanna Mountain showed me one feature on the 23andMe website that makes my Ashkenazi ancestry especially apparent. My 23 chromosomes are displayed as separate bars — and each one of them is covered with bright blue sections, representing all the gene segments I share with other people in their database whose ancestors were also Ashkenazi Jews. Looking at that chart, Joanna Mountain said to me, "This is where your Jewish ancestry really pops out."

Mountain also explained to me that this is how testing companies determine ancestry: they compare your genes to known reference populations to see which ones they resemble most. The closer you are to the reference data, the more likely it is that you have that same ancestry.

In addition to 23andMe's analysis, I ran my data through other publicly available programs (for example, the Interpretome site and Euro-DNA-Calc) and they all gave me the same result: my genes are extremely similar to the genes of other Ashkenazis.

That's not to say that I had no overlap whatsoever with other groups: my DNA did bear some resemblance, for instance, to the genes of Moroccan Jews, Italians, North Africans and Tunisians. But that overlap was trivial compared to the number of identical gene segments I shared with Ashkenazis.

A Complicated History

Despite the large proportion of segments I shared with other Ashkenazis, I was still curious about the other groups that had contributed to my DNA… but that's where the story gets complicated. This is because the history of Jews in Europe is a convoluted one, and lots of the details are sketchy — which makes it hard to study Ashkenazi genes.

There are different hypotheses about how Ashkenazi Jews came to Europe and how they mixed with local populations. Bennett Greenspan of Family Tree DNA explains one possibility: "When the Romans expelled the Judeans approximately 2,000 years ago," he says, "they deported mostly the trouble makers, which meant that they probably deported more men than women, and yet when those Judean slaves were looking for wives in Italy, they reached out into the local Italian non-Jewish population and converted women, and married those women and the rest was history."

After that initial injection of Italian DNA, some think the Ashkenazi population may not have mixed much with other groups in Europe. But David Goldstein, who directs the Center for Human Genome Variation at Duke University, says there's another possibility. "I think what's happened is, there's always been some little degree, at least, of interchange between Ashkenazi populations and all these different peoples that they have lived amongst. And so it is an incredibly complicated history of input from all sorts of different populations, and we're not going to unravel that."

What that means is that while it's true that as a group, Ashkenazis clearly have a European contribution to their DNA, right now that's as far as the science will take me when it comes to my own family history. So two hundred dollars and a vial of spit later, the big headline is something I already knew: that my ancestors were mostly Jews from different parts of Eastern Europe. In other words, I'm exactly who I always thought I was.

I have to admit that I was a little disappointed that the testing didn't tell me anything more specific. Don't get me wrong: it's amazing that a scientist can look at my DNA and see that I have ancestors from Belarus or Russia, just like my grandparents told me. But just think how cool it would have been to have found something completely unexpected in my results, like being Norwegian, or Native American…or even Scottish. Maybe I just wanted a surprise — or at the very least, more answers to some of my questions.

The Mitochondrial Connection

I did get one hazy glimpse into my past, via my mitochondrial DNA — that's the special piece of DNA that's handed down from mother to child. Mitochondrial DNA is separate from your 23 chromosomes, and it's useful because it has mutations that can be traced to a common ancestor. It's divided into subgroups called haplogroups, and each haplogroup traces back along the maternal line to the female ancestor in whom the identifying mutation of that haplogroup first appeared. In my case, my haplogroup — H3 — traces back to a common female ancestor in Southwestern Europe (Iberia) about fifteen thousand years ago.

Today, H3 is one of the most common haplogroups in Western Europe. However, it's not very common among Ashkenazi Jews — which raises the question of how it got into my maternal line in the first place. Family Tree DNA's Bennett Greenspan says we can speculate about the female ancestor I got it from:

"My guess is that if we went back far enough on your mother's mother's mother's mother's direct female line, that we would probably find that she was a non-Jewish woman who married a Jewish immigrant or deportee into Europe sometime over the last few thousand years."

Taking that speculation one step further, 23andMe's Joanna Mountain says that since one branch of the H3 population spread along the Mediterranean and across the Alps into what is now Hungary, where I know some of my ancestors once lived, that's probably the H3 line that my mitochondrial DNA comes from.

"And then your Jewish ancestors arrived in Hungary," says Mountain, "and the simplest story we can draw is that one of those Jewish ancestors married a woman from Hungary or nearby, but the children remained within the Ashkenazi Jewish community."
Not Much the Wiser… Yet

Of course, I don't really know if my H3 mitochondrial DNA came from a woman who lived in Hungary in the recent past, or whether it came from a female ancestor who lived somewhere else, a very long time ago perhaps. But given the red hair in my family and the history of Jews in Europe, it's not at all surprising to have some DNA from an ancestor who probably wasn't Jewish. Still, I'm not much the wiser about my family history than I was when I started all this. That could change soon, however. Sometime in the next decade, the cost of having your whole genome sequenced — all three billion letters of the code — will become affordable. When that happens, says Harvard's Joe Pickrell, that's going to change everything all over again.

"What you'd be able to do is look at an individual's genome and say, all right, they have this mutation, which arose in a particular village in the south of France, for example, and then you'd be able to say with nearly a hundred percent certainty that you have some ancestor who came from that particular village."

Geneticist Daniel MacArthur agrees. "With whole genome sequencing we'll be able to look at the variants found only in one very small area of Europe," MacArthur says. "So if they had a large enough collection of reference individuals and your entire genome sequence, we can pin down your location pretty precisely I think — particularly if all of your ancestors come from one region."

The Caveman Connection

So now I guess I'm waiting for the day when I can afford to have my entire genome sequenced. But in the meantime, the most exciting thing I've learned about my ancestry may be something that goes back a lot further than any European village. In fact, it goes all the way back to the Stone Age.

Recent studies suggest that humans may have interbred with Neanderthals tens of thousands of years ago. And not long ago, the 23andMe website added a feature that lets you see what percentage — if any — of your DNA comes from Neanderthals. So I navigated to the relevant webpage, clicked on the link and got my result: according to 23andMe, 2.7% of my DNA is Neanderthal. And while that's not unexpected — almost all people of non-African descent do have a little bit of Neanderthal DNA in them — I find it strangely compelling to think that somewhere up the line, many thousands of years before the red hair and the mitochondrial DNA were part of the story, before the dawn of recorded time or the existence of words like "Europe" or "Ashkenazi," I was a twinkle in a Neanderthal's eye.

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