I grew up wishing I were white, but there was no disguising the thick black hair, straight bangs, and slanty eyes. Most of the time I smelled like pad thai. Then again, I wasn’t exactly Asian, either. I have always fallen somewhere in between the tidy categories that people like to make.
My Thai mom left her country for America when she was in her early twenties, and she met my white, 6-foot-4 dad at the University of Florida. We celebrated major holidays—Christmas, Thanksgiving, Easter—with my European side of the family. But Mom clung to everything that made her Asian, and she did a good job of making me look like a little Thai girl, especially when she put me in Asian dresses and dragged me to Asian parties.
Now that I am an adult, I embrace the Asian-ness in me. I have developed an obsession with sushi. On the other hand, I don’t look as Asian as I did as a child, except when I drink red wine and my cheeks flush and my eyes get small and squinty. Whichever way I turn, my identity is not transparent: Although my mom grew up in Thailand, she had Chinese parents. My dad’s ancestors came from England, Germany, and Ireland.
Like me, many Americans want to learn more about who they are and where they came from. In the past, people flipped through old phone books, explored overgrown churchyards, and pored over immigration records and birth certificates to build their family trees. Today the business of genealogy is going genetic, as entrepreneurial scientists hijack the kinds of DNA analysis previously used to determine evolutionary relationships and give them a personal spin.
In 2000, Houston-based Family Tree DNA became the first company to market DNA-based reports about an individual’s ancestry. Since that time, more than two dozen companies have entered the field, and some 460,000 people have purchased genetic ancestry-testing kits from them.
The rise of DNA ancestry testing has led many people to think that they can now buy detailed and rigorous information about their racial, ethnic, and familial backgrounds. I decided to find out for myself. Last fall I took tests from three major DNA ancestry companies to see if they could tell me anything about my identity that I didn’t already know.
I started with the most basic test, offered by the Genographic Project in Washington, D.C., which traced my maternal ancestry. Then I had my dad take a test from Family Tree DNA to track my paternal lineage. Finally I submitted my DNA to 23andMe, a company in Mountain View, California, that scoured chunks of my genome to tap into my ancestry on both my mother’s and my father’s sides.
The Genographic Project: Testing My Maternal AncestryCommercial testing companies do not need to test my whole genetic sequence—all 3 billion nucleotides, the “letters” of the genetic code—to tap into my past. Instead they search specific regions of the genome for a type of mutation known as a single nucleotide polymorphism, or SNP (pronounced “snip”). A given SNP could have started with one person who lived tens of thousands of years ago; over time, that person’s descendants would have carried on the mutation, along with others acquired later, as they migrated. Those are the mutations ancestry companies look for when placing a person into one of the 20 “haplogroups,” the major genetic branches of the human family tree.
I sent away for my kit from the Genographic Project ($99.95; nationalgeographic.com/genographic) knowing I would get information only from my mom’s side of the family. DNA that provides information about ancestry exists in the nucleus of the cell but also in the mitochondria, the energy-generating powerhouses that are scattered throughout the cell. Unlike nuclear DNA, which comes from both parents, the DNA from mitochondria (called mtDNA) is inherited solely from the mother. The Genographic Project studies the SNPs in that mitochondrial DNA to see what mutations were passed along through the maternal line.
When my mtDNA collection kit arrived in the mail, I opened it eagerly; inside I found a stick for scraping cells from the insides of my cheeks. After doing so, I placed the end of the stick into one of the sanitized vials included with the kit and sealed the vial with a lid. I repeated the process after two hours and again later in the day. Then I sent the three samples off and waited.
Several weeks later, from my work cubicle in New York City, I logged on to the Genographic Project’s Web site using my kit ID number and printed out my results. I received a goofy certificate with my name on it telling me that I belong to haplogroup D. All the members of my haplogroup share a particular set of mutations in mtDNA. The rest of the package included a map that traced the migration of my haplogroup over tens of thousands of years.
I am descended, the document explained, from a “Mitochondrial Eve” who lived in Africa about 150,000 years ago. Eve’s descendants split into haplogroups L1 and L0, both of which originated in East Africa. Further mutations created another haplogroup that became widespread among women in West Africa. About 60,000 years ago my ancestors from that area left Africa for good. The next major mutation gave rise to haplogroup M; many descendants of this group today live in Pakistan and northwest India. Finally, some 50,000 years ago, my haplogroup, D, appeared in the Central Asian plains and began moving throughout East Asia. And now here I am.
I found this information rather disappointing. My ancestry report was mostly a generic account of ancient human populations. But the Genographic Project’s main goal is not to answer questions about personal identity; its purpose is to collect as much genetic information as possible from people around the world. The resulting database will become a master file of DNA samples that can answer a wide range of questions about modern humans’ ancestral backgrounds, before influences like international travel scramble this information for good. The more participants like me are willing to share their genetic information, the more the Genographic Project will know about smaller, more local migrations. So I filled out a form telling the project that my father’s ancestors were English and my mother’s were Chinese.
I wanted to know whether the Genographic Project’s test could tell me more about myself. I called population geneticist Spencer Wells, the project director, who spends much of his time in the field collecting DNA. “Your mother seems to have more of a northern version of haplogroup D,” he told me—more northern, that is, than the patterns typically seen in Thailand and Southeast Asia. My mtDNA just confirmed what I already knew: My grandmother had come from China, not Thailand.
Family Tree DNA: Examining My Father’s Y ChromosomeNext I explored the other side of my ancestry. Family Tree DNA’s Y chromosome test ($119, familytreedna.com) looks for SNPs and small stretches of repeating nucleotides on the Y chromosome that fathers pass on to their sons. Random mutations (generally harmless) that occasionally arise in these sequences are passed along too. The genetic signatures of the mutations are a lot like inherited surnames. Since only men have a Y chromosome, I had to ask my father to use the Family Tree DNA kit that would arrive in the mail. I assured him that it wasn’t a paternity test.
The company sent my dad a kit that looks at 25 markers to place him in one of the 20 haplogroups. My dad told me he had almost gagged while scraping the inside of his cheek three times for cell samples. But at least he did not break the stick. He sent the samples to a company lab in Houston for analysis.
A week later we were able to view the results online. “Out of 165,000 men in the database and out of the 50 or so Dickinsons, we eliminated all but three,” Bennett Greenspan, the founder and CEO of Family Tree DNA, told me. “If you’re a genealogist, you compare your dad’s genealogy with the men who match him to find out who your common ancestor is.” The three matches turned out to be cousins of my father’s, but according to Greenspan, “DNA can’t tell you whether you are a first, third, or fifth cousin because these markers change randomly.”
I was in a cab on my way home from a restaurant when my dad called with news. “Guess what?” he said eagerly. “I got more of my DNA results. I’m mostly from eastern England where the Puritans are from. I belong to haplogroup I2a.” This didn’t surprise me; I2a is a branch of haplogroup I, to which 20 percent of all Europeans belong. Even my father’s specific branch, haplogroup I2, is pretty common.
Suddenly I felt like a child again—under the covers with my pajamas on, listening to a bedtime story—as my father told me about our migration history. “You see, Boonsri, the I2 people are the mammoth-eaters portrayed in The Clan of the Cave Bear,” he told me. People who belong to the I2a subgroup are probably from the Balkans and Sardinia; judging from the accumulation of mutations, this group split from haplogroup I about 25,000 years ago. My father must have descended from a pocket of people in Eastern Europe that migrated to England, perhaps along with the Roman army. The Puritan Dickinsons then moved to New England.
My dad said the report confirmed everything he had already known about our genealogy, particularly the English part. After his father passed away, he discovered his family is related to Emily Dickinson. The connection is not direct, since she did not have any children, but her grandfather’s brother was an ancestor of mine.
23andMe: Scanning for Genome-Wide Associations Much of the recent hype in ancestry testing has focused on genome-wide association tests, which can rapidly scan hundreds of thousands of SNPs. So for my third sample I ordered the kit for such a test from 23andMe ($399, 23andme.com). The company examines more than 550,000 SNPs and looks for associations to predict a person’s risk of common diseases, but it also roots out ancestral information. I decided to see this process live in the lab.
I drove to the top of a cliff in San Diego and stood before the daunting yet delicate glass structure that houses Illumina, the lab to which 23andMe had outsourced my sample. The pristine building is the size of a football field; reflections of the bright California sun nearly blinded me as I entered. Inside, I toured the state-of-the-art DNA sequencing facility. Technicians were dressed in white lab coats, shower caps, and gloves as they tested mailed-in samples for markers in all parts of the genome—not just the mtDNA and not just the Y chromosome.
When I returned home and logged into my 23andMe account, my data popped up in a Facebook-like page that listed my risk of various diseases as well as a report of my ancestry. “Friends” who shared their genomes with me were listed along the right side of the page. The report added some details about my place in haplogroup D: I belong to subgroup D4a. “Your maternal ancestor was probably from Siberia and northern China,” Joanna Mountain, senior director of research at 23andMe, explained. People in subgroup D4a have a gene for longevity, consistent with what I know about my grandmothers and great grandmothers, who all lived well into their nineties.
23andMe provided a map to show where my ancestors came from, but the results could not properly represent my mixed ethnicity. The company’s computer analysis correctly determined that roughly half my DNA came from Europe and half came from East Asia. Then, drawing a conclusion that only a computer could draw, it split the difference and indicated I was most genetically similar to people halfway between the two, in the middle of Central Asia.
A big part of the problem is the difficulty of cross-checking the results. “Your ancestry results totally depend on the genetic database the company has collected so far,” says Deborah Bolnick, a biological anthropologist at the University of Texas at Austin. “Obviously, not everyone in the world has had their DNA tested, and so companies must rely on their own proprietary databases.”
In the end, 23andMe’s whole-genome approach again mostly repeated details I already knew about my family and added nothing to my understanding of our recent history of migration. The next time I get the question people always ask when they meet me—Where are you from?—I’m not about to say, “I’m from haplogroup D4.” It will be a long time before ancestry companies can provide truly meaningful details at that level.
What Comes Next?
The most exciting thing in ancestry testing is happening not in the commercial market but in the research labs. At Harvard University, geneticist David Reich is applying a technique called admixture mapping to study the history of people of mixed descent, analyzing stretches of DNA to see where they come from and when mixing first occurred. He has compared the genomes of indigenous populations in Africa and Latin America with the genomes of similar peoples who migrated and intermarried with other populations during the past several hundred years.
Reich finds that African Americans have patterns of genetic variation unmistakably different from those of the people in their ancestral country; Latin Americans have also diverged from the indigenous people of their native countries. These results show how the genome can record migrations on timescales of hundreds of years, not just thousands.
George Church, another Harvard geneticist, is working to speed up the sequencing and analysis of a person’s entire genome. Once that becomes available to the general population at an affordable price, he says, geneticists will be able to track your DNA letter by letter across generations to find out whether a rare trait was inherited from your mother or from your father or acquired through a unique mutation. At that point, ancestry testing will become powerful and family-specific.
If only my results had been as impressive. The expanded sense of identity that I got while researching this article came mostly the old-fashioned way. I trekked cross-country to visit 23andMe, rode the bus to meet researchers at Penn State, and had new kinds of conversations with my father. Recently he told me that my great-grandfather had died from epilepsy at a young age, filling in one more piece of my family history.
Clearly I had hoped for too much from the ancestry tests. In the future, DNA databases will expand and the new-style genealogists will get better at interpreting our genome. But the events that define who we are will continue to unspool as they always have—through experience and serendipity.