Augusta Genealogical Society: DNA can unlock family connections

Have you considered having your DNA tested? If you haven’t, maybe you should. But first, some explanation is needed.

 

We each have 46 chromosomes, 23 from each parent. One pair of the chromosomes determines sex. All babies inherit an “X” chromosome from their mothers. Babies who inherit an “X” chromosome from their fathers are XX and therefore female. Babies who inherit a “Y” chromosome from their fathers are XY and therefore male.

There are 3 types of DNA tests: Y-DNA, mtDNA (mitochondrial) and autosomal DNA.

YDNA – Since only men have Y DNA, only men can take this test. It traces the sex-determining chromosome that passes from father to son, tracing the straight male line, father, father’s father, etc. It doesn’t provide information on any other lines.

MtDNA (mitochondrial DNA) – Both men and women have X chromosomes so anyone can take this test. It traces the chromosome that passes from mothers to all of their children regardless of the children’s gender, tracing the straight female line, mother, mother’s mother, etc. It does not provide information on other lines.

Autosomal DNA – This test is done on the 22 non-sex-determining chromosomes called autosomes. Anyone can take this test, which provides a broad overview of a person’s ancestry. A number of companies do this test. Among them are Ancestry.com, 23andme.com, and familytreedna.com.

The autosomal DNA test can identify the parts of the world from which your ancestors came. People from all over the world have been tested, allowing scientists to identify certain markers or slight differences that are associated with people from certain regions. By looking at these markers, scientists can use DNA to tell you the regions of your ancestors.

Most continents can be divided based on DNA into a number of regions. Each region usually encompasses several modern countries. In Europe, for example, Ancestry DNA lists a number of regions including “Great Britain” (mainly England); “Ireland,” which includes Ireland, Scotland and Wales; and “Europe West,” which includes Germany, France, the Netherlands, Switzerland, Belgium, Luxembourg and Liechtenstein.

In Africa, Ancestry DNA has “North Africa” and eight sub-Saharan regions including “Ivory Coast/Ghana,” “Cameroon/Congo,” “Nigeria,” and “African South East Bantu” among others.

Asia is divided into “Asia East,” which includes China, Japan, Korea, Vietnam, Indonesia and several other countries; “Asia West,” which includes the Middle East and the Caucasus; “Asia Central,” Afghanistan, Kazakhstan and others; and “Asia South,” which includes the countries of the Indian subcontinent. There are also listings for Polynesia and Melanesia. The entire inhabited globe is covered. It should be noted that many countries in Europe and elsewhere are “admixed,” which means that natives of those countries usually have some DNA from other, typically neighboring, regions.

If you have ancestors who have been in America for many generations, it can be very hard to “cross the ocean” through record research to find out from where they came. Colonial and 19th-century record-keeping (or lack or destruction thereof) can make it difficult. DNA leaps across the Atlantic or Pacific Ocean as if it wasn’t even there.Apart from Native (aboriginal) American DNA, America hasn’t been settled long enough to have its own DNA, so unless you are Native American, your DNA will take you across the ocean.

If you have a researched tree and have had your DNA tested and have them both on-line at a site such as Ancestry.com, the DNA can also:

1. Help to confirm your research. If you have DNA links showing that you match a number of people who descend from a certain ancestor, it indicates that your research is most probably correct and that you actually do descend from him. If he is a fairly recent ancestor and you don’t have any matches who descend from him, you may need to re-check your research.

2. Help you find some unknown ancestors. If you don’t know a particular female ancestor’s maiden name, for example; but you find a number of DNA cousins whose research shows that they descend from one man, say John Franklin, and he lived in the area where you suspect your female ancestor lived and is the right age to have been her father, you may have just found her father. You can then do research to confirm or disprove this hypothesis by checking a name you would never have thought to check before. Not only may you have found her father, but your DNA cousin may have traced the line several generations further back. If so, some websites, such as Ancestry.com, let you see this and let you contact your DNA cousin through his screen name. DNA is still relatively new, and genealogy websites are still adding helpful new ways to search it for connections.

What can DNA testing not do? It cannot tell you the actual names of ancestors or when they came to America. To find the actual names of ancestors you have to do genealogical research.

We don’t get DNA from all of our ancestors. We have DNA from our parents, grandparents, and a few generations further back. Beyond that we each get DNA from some of our ancestors, but not from all of them. Each generation receives only half of its parents’ DNA. The other half is dropped. Genealogists distinguish between a “genealogical family tree” that is basically a list of all known ancestors and a “genetic family tree” that is basically only the ancestors from whom a person has DNA. Even if you are descended from, say, Charlemagne, after so many generations you probably don’t actually have any of his DNA. Only a very small percentage of his descendants do.

You should not have a DNA test done unless you are sure you want to know and can accept whatever it tells you. If you or one of your ancestors were adopted and don’t know it, your test may make you realize it when you find you aren’t related to the people you thought you were. It may have been a matter of adoption (formal or informal) or a wife having a child from a prior marriage that you didn’t know about, or a matter of marital infidelity in some prior generation.

Genealogists even have a term for this, “Non Parental Event (NPE).” You may also find that you have a small percentage of DNA from a race or ethnicity that you didn’t expect. Some people have concerns about confidentiality. Most sites have rules posted on their websites about confidentiality.

How is DNA tested? The person who wants to be tested orders a test kit. The kit has a cotton swab, a test tube, a package to mail it back in, and simple instructions. The person follows the instructions, swabs the inside of his cheek with the cotton swab, puts the cotton swab into the test tube, seals the tube, puts it into the pre-addressed package and mails it to the company. In a month or so, the person gets his results. The cost is usually about $100, although the tests sometimes go on sale.

DNA testing does NOT by any means take the place of a researched family tree, just as having a researched family tree does NOT take the place of DNA testing. The two complement each other, providing a much more complete picture of your ancestry. Paired with a carefully researched family tree, DNA testing can be a powerful tool for the genealogist.

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