Tracing Your Family History with DNA Testing
Tracing your family history can be frustrating at times. Often people hit a wall when the paper trail about their family ends. A tool that more and more genealogists are using to get around these walls is DNA testing.
Using DNA testing to trace family origins is called genetic genealogy. If you’re interested in genealogy, it may be something you want to think about.
What is DNA, and how is it useful for genealogy?
Almost every cell in your body has a complete set of your inherited genetic information. It is stored in twisted strands of DNA (deoxyribonucleic acid) called chromosomes. DNA carries the information in the form of a code.
Each chromosome contains thousands of genes (also called coding DNA). Genes determine specific traits, such as your hair color, eye color and blood type. But genes make up only a small amount of the DNA. In between the genes are long sections of non-coding DNA.
Over time, slight changes occur in the non-coding DNA. These changes get passed down from one generation to the next. By looking at changes in the non-coding DNA, genetic ancestry testing can often identify people who have the same ancestors.
How is DNA ancestry testing done?
The test itself is very simple. You swab the inside your cheek and then mail the swab to a lab. The lab extracts the DNA and compares it to other samples in a database of haplotypes (sets of inherited genetic markers) to see if there is a match.
There are two types of DNA tests:
Y-DNA. The Y chromosome is passed from father to son, so the Y-DNA can be used to trace a man’s paternal ancestry.
mtDNA. Mitochondrial DNA (mtDNA) comes only from the mother, so it can be used to trace maternal ancestry.
These tests can run from about $100 for the simplest ones to around $1,000. The cost depends on what type of DNA is tested and how many markers are tested.
Can these tests tell me about both my paternal and maternal ancestry?
Both men and women have mtDNA. So a man can choose to trace both his maternal (mtDNA) and his paternal ancestry (Y-DNA). A woman doesn’t have a Y chromosome, so she can only trace her maternal ancestry.
If you’re a woman, though, you can find out about your paternal ancestry by asking your father or brother to be tested and share their results.
Is this the same type of testing used to test for genetic diseases?
No. Ancestry testing looks at specific areas of non-coding DNA that are not involved in your health or development.
What can I learn about my ancestry from genetic testing?
You could gain some information about your ethnic and geographic origins. You will find out where your recent ancestors came from and where your ancestors came from in the distant past.
If you agree to share your information, your results will be placed in a database. If you and someone else have a close match, both you and other person will be notified. Some people have found relatives this way.
What else should I think about?
It’s important to understand that:
These tests will not provide you with a family tree. They may give you information that will help you fill gaps in your genealogical research, but they don’t take the place of this research.
You will only learn about a very small slice of your background. If you go back 10 generations, you have 1,024 ancestors. A Y-DNA test or mtDNA test will only give information on about one individual in each generation.
The outcome may not be what you expect. In some cases, these tests reveal genetic information that conflicts with accepted family history. For example, some African Americans have learned that their male line came from Europe instead of Africa. Some people have discovered that they were adopted or that they had a different father than they thought.