How to Use DNA Testing for Genealogy Research

Your DNA is what makes you who you are - can it help you find out who your ancestors were?
Chad Baker/Ryan McVay/Digital Vision/Thinkstock

Have you ever wondered about the origins of your family or tried to create a family tree? Just a few years ago, researching your family might mean lots of legwork. You might have to visit graveyards, libraries and courthouses in several towns. Then, you'd search through records to match up names and fill in gaps. The process, while rewarding, is daunting.

Science and technology have made it easier to get an idea about your origins. True genealogical research still takes work, but you might not have to travel quite as much to get the same results. Many towns have begun to make their records available online. And if that's not enough, dozens of companies now offer to examine your DNA to help you learn more about your ancestry.


Humans share about 99.9 percent of the same sequence of DNA. Only about 0.1 percent of the sequence is different among various groups of humans [source: Skloot]. Regional populations of humans tend to share many of the same genetic markers. By comparing your DNA to a database filled with other subjects' DNA sequences, genetic testing companies can give you an idea of where your ancestors came from.

It's important to note that the information you get from a DNA genealogy test is general and probabilistic. That means the answers are based on statistical probabilities -- they aren't hard and fast facts. While some genetic markers may be commonly found in one particular population, that doesn't mean they're unique to that people. It just means you're statistically more likely to be related to those people than other groups.

If you're submitting just your own DNA, you'll get results that will tell you more about your genetic makeup. If you're male, you can perform a Y-DNA test to find out where your paternal line comes from (women lack the Y chromosome ). Men and women can perform a mitochondrial DNA (or mtDNA) test to learn about where their maternal line comes from. You can even determine if you're related to someone specific if you're able to submit DNA samples from you and the other person.

As companies build out their databases, they uncover more information about human populations. In fact, your DNA haplogroup -- the genetic population you belong to -- might change. This doesn't mean your DNA changes. It just means that as we learn more about our ancestors we refine our definitions and classifications.



How to Get a DNA Test for Genealogy Research

Family tree
A DNA test can help you get in contact with people who share a common ancestor, but it won't magically fill out your family tree
Hemera Technologies/

There are several companies that offer DNA genealogical tests. The first thing you should do is research the company. Make sure the company has a good reputation. Each company relies on its own proprietary database of DNA information. The larger the database is, the more accurate your results will be. And a respected company is more likely to stick around long after you take your test. Some companies will even send you updated information about your results as they refine their databases.

The tests themselves are simple and painless. Most involve using a type of swab. You use the swab to collect cells from the inside of your cheek. Just rub the swab against your inner cheek for about half a minute and you've collected enough of a sample to get a bead on your genetic background.


Tests can be expensive, ranging from around $99 up to several hundred dollars depending on the type of test. Before you order a test, you should be aware of what the results will mean to you. A DNA test can help you fill in gaps in your family tree or determine if someone with the same surname is directly related to you. But DNA tests won't give you the information you need to fill out your entire family tree. It's a useful tool but not the only one you'll be using to research your genealogical background.

If you're male and want to research your paternal line, you'll need to order a Y-DNA test from a reputable company. If you're female but want to know more about your paternal line, you'll need to have a male relative perform the test for you. If you're more interested in the maternal line, you'll need to order an mtDNA test. Both males and females can perform such a test on themselves.

Some companies offer different versions of the Y-DNA and mtDNA tests. Usually this means that one test uses more genetic markers than the other, giving you a more accurate glimpse at your family background. If you're trying to find out more about your particular surname, you'll need to order a test that looks at more markers than a general ancestry test. You may find some companies offering package deals in which you can order both a Y-DNA and mtDNA test. Other DNA tests can tell you if you're related to a specific person -- both people need to take the test.

Getting a test is as simple as ordering the right test kit from the company you have chosen. The company will ship the test to you. Once you take the test, you send the sample to the company for analysis.


Where to Post DNA Test Results for Genealogy

DNA test results
One criticism some researchers level at DNA testing companies is that their results can be difficult to understand.

Once the company you've chosen completes the analysis of your DNA, it will send you the results. Some companies will give you the option to include your results in a special database. If other customers have results that match yours, the company can contact you and the other people to let them know of the match. A match means that you share an ancestor with the other customer, though it's impossible to determine how far back that ancestor might be from the results alone.

By getting in touch with people who match your results, you may be able to fill in the gaps in your family's history. You may also discover distant cousins who split off from your branch of the family many decades ago. Your results will help the company refine its classifications -- each customer's data adds to the bigger picture.


Some testing companies create profile pages for customers on their Web sites. It's like joining an online social network. This can help you get in touch with other customers of that company who have similar results to your own.

There are also genealogy Web sites where you can create an account and post your results. You may wish to search your surname -- many surnames have Web sites dedicated for genealogical research. Or you can post the results to your own personal site. You can even post the haplogroup you belong to, but haplogroups are very general -- they just define genetic populations. A genetic population isn't necessarily linked to a particular ethnicity, culture or even geography. And the classifications for haplogroups for Y-DNA results are different than those for mtDNA results.

It's only by looking for marker matches that you'll start to uncover possible relatives. If you and another person have several markers that match, there's a chance you may be related. The more marker matches you have, the more likely you share an ancestor within a few generations.


DNA Genealogy Projects

There are dozens of genealogy projects currently active. They range from regional to global in scope. Some are meant to give a big picture glimpse of how people migrated from one region to another over millennia -- these are more anthropological than genealogical in nature. Others help people get in touch with fellow genealogists to solve mysteries and connect to family members who may be separated by geography and generations alike.

One of the largest projects is the Genographic Project spearheaded by National Geographic. You can participate in the Genographic Project by purchasing a test -- it costs around $100 -- and submitting your sample to the project. It's not meant to help you find out who your great-great-grandfather was. Instead, the project's aim is to map the migratory patterns of human history. It's about as big a picture as you can get.


The USGenWeb Project is a volunteer organization dedicated to helping citizens of the United States research their family backgrounds. The project has links to each state project. Within the state project site, you'll find links to resources that might help you find out more about your family. In many cases, the links will tell you where you need to go to see official documents that have your family's information on them. You'll still need to do some legwork to fill in the gaps, but the projects resources can give you a good place to start.

The WorldGenWeb Project has similar goals but on a global scale. It contains links to regional genealogical project Web sites. Volunteers can elect to oversee a particular region. It becomes that volunteer's duty to gather research resources and create forums for members to connect with one another and discuss family histories.

Many surnames have their own DNA projects. Most of these projects began as personal projects that grew over time and merged with other projects for the same surname.

Keep in mind that these projects are meant to help you in your search for information about your family. Don't expect them to present your complete family history through a single search query. You'll most likely need to do additional research and contact distant relatives to build out a full history.


Lots More Information

Related HowStuffWorks Articles

  • Ancestral Origins DNA Testing. (April 15, 2010)
  • Bettinger, Blaine. "Is Genetic Genealogy a Scam?" The Genetic Genealogist. April 25, 2007. (April 19, 2010)
  • Bolnick, Deborah A. et al. "The Science and Business of Genetic Ancestry Testing." Science Magazine. Oct. 19, 2007. Vol. 318. pp. 399-400.
  • DNA Tribes. (April 15, 2010)
  • FamilyTreeDNA. (April 15, 2010)
  • Hawks, John. "How African Are You?" Slate. March 15, 2006. (April 16, 2010)
  • National Geographic. "The Genographic Project." (April 16, 2010)
  • Sills, Jennifer, editor. "The Legitimacy of Genetic Ancestry Tests." Science Magazine. Feb. 22, 2008. Vol. 319. pp. 1039-1042.
  • Skloot, Rebecca. "Putting the Gene Back in Genealogy." Popular Science. Dec. 24, 2003. (April 16, 2010)
  • Skloot, Rebecca. "The Bogus-ness of DNA Testing for Genealogy Research." Culture Dish. June 12, 2006. (April 16, 2010)
  • Smolenyak, Megan. "Genealogy by DNA: Can it Deliver?" (April 19, 2010)
  • Smolenyak, Megan. "Honoring Our Ancestors: Is Genetic Genealogy Being Oversold?" June 28, 2006. (April 19, 2010)
  • The USGenWeb Project. (April 20, 2010)
  • U.S. National Library of Medicine. "Genetics Home Reference." April 18, 2010. (April 19, 2010)
  • WorldGenWeb Project. (April 20, 2010)