Archive for March, 2013

Is DNA Right for You?

Friday, March 1st, 2013

Anyone who has watched television in the past two decades knows the value of DNA evidence. Comparing two samples of DNA is a great way to convict or exonerate a suspect or to identify a victim. If two samples of human deoxyribonucleic acid are identical, they came from the same person, because DNA encodes all of a person’s genetic information, and no two people have exactly the same DNA. It’s better than fingerprints. DNA can also show relationships between two people, because relatives have similar (but not identical) DNA.

The idea of using DNA for genealogy inspires images of digging up old grave sites to procure a sample. But you won’t need a shovel. You yourself are a walking record of your ancestors. Some pieces of your genetic makeup have come from recent ancestors; others have been handed down from generation to generation over hundreds of years.

DNA Double Helix

Your DNA determines the characteristics you inherit from your parents. For genealogy testing, specific markers (snippets of genetic code) on the last chromosome pair have been identified as the most stable markers, that is, they remain most consistent over time. Some of your inherited traits may be obvious; you may have your father’s nose and your grandmother’s toes. But your DNA also contains less obvious traits which come down to you from more distant generations.

This means that your DNA includes a record of long-forgotten ancestors.

There are three main types of DNA tests used in genealogy.

Y-DNA

We all inherit an X chromosome from our mother. Males also receive a Y chromosome from their father.

Testing of the male line includes looking at shared markers on the Y chromosome. Depending on how much detail you want, you may look at 12, 37, or 67 markers.  Because the Y chromosome is only passed through the paternal line, Y-DNA testing can only be administered to a male. The results provide insight into the male ancestors of that individual’s paternal line, including identifying the haplogroup — essentially, your place in the genetic tree of the world.

mtDNA

Mitochondrial DNA (mtDNA) is contained in the cytoplasm of the cell, rather than the nucleus. This type of DNA is passed by a mother to both male and female offspring without any mixing, so your mtDNA is the same as your mother’s mtDNA, which is the same as her mother’s mtDNA. mtDNA changes very slowly, so it cannot determine close relationships as well as it can determine general relatedness. If two people have an exact match in their mtDNA, then they share a common maternal ancestor, but it is hard to determine if this is a recent ancestor or one who lived hundreds of years ago. It is important to keep in mind with this test that a male’s mtDNA comes only from his mother and is not passed on to his offspring. Your maternal line haplogroup is identified with an mtDNA test.

The DNA tests that identified the bodies of the Romanovs, the Russian imperial family, utilized mtDNA from a sample provided by Prince Philip, who shares the same maternal line from Queen Victoria.

Autosomal

The newest form of DNA testing for genealogy is called Autosomal testing. Over 700,000 locations on the DNA are tested to identify any shared ancestor within the last five generations. You also will gain insight into your ethnic makeup. If you’ve reached a dead end in your research, to the point that you don’t even know where to look, autosomal DNA testing can give you some direction. It will also help you to connect with living relatives whose DNA is on file for comparison.

At the St George Family History Expo this month, I listened to a wonderful talk given by a representative of The Genetic Genealogy Consultant. She shared a story of connections her own autosomal test results made possible. Getting in touch with a matched relative allowed her family to reconnect with a distant cousin who spent hours and hours with her father in their childhood but had since lost touch.

Picking a test

DNA testing can be both exciting and overwhelming. Whether you are looking for new insights into your existing pedigree, a place to start, or ways to connect with living relatives, there is information in your DNA that will unlock resources and leads for your research.

If you are like me, you don’t readily spend your hard-earned money on the latest, greatest technology. I have yet to switch over to a smart phone, much to my colleagues’ amusement,

Choose a DNA test based on which line you want to explore.

because every year there is something better. In the past much of the benefit of DNA testing was to add to the research and development of the field. In order for results to be meaningful, they must be compared with known markers. Family Tree DNA has the largest database, including DNA information on over 400,000 people. The field of genealogical DNA testing has arrived. It has become a dependable treasure trove of information to expand your traditional research efforts, and it will only get better.

To choose which kit or kits are right for you, look at your pedigree and decide what you would like to find out. For example, I’m stuck in the 1800s on my grandfather’s father’s line. I’m told there is German blood, but the surname is Scottish. The best thing for me to do in this case is to find the oldest living descendant in that line and test their paternal line with a Y-DNA test. If I am interested in my mother’s mother’s Irish roots, I need to administer an mtDNA test to my Mother or a female descendant of that line.  All it takes is a simple and painless cheek swab. (Watch this tutorial.)

Know What to Expect

It is important to know what to expect from your results. The report you receive can be very technical. Don’t despair if your high school biology is a bit rusty. There are many wonderful help articles to help you through the details. For example, this one at the Blair DNA Project gives insight into what a DNA test can do for you. Here is a good list they give of insights you can gain from your results:

1)      Identification that you and another participant share a common ancestor.

2)      Y-DNA and mtDNA results give you an idea of how far back a common ancestor lived and the migration path of that ancestral line through the identification of the maternal or paternal haplogroup.

3)      Evidence of a suspected connection between yourself and another participant.

4)      Prove that the test taker is not related to an individual or family.

5)      Autosomal test results provide an amazing detailed description of your ethnic makeup.

Finally, remember that DNA testing alone is not as meaningful as DNA testing paired with traditional research. To get the most out of your DNA test results, use the information as you would any new development in your search. It will open doors and suggest new connections. Ask for help from a professional, if you are not sure how the results can expand your tree.