Marty & Karla Grant

DNA Information

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Have you heard about the latest tool available for tracing your genealogy? I’m referring to DNA testing. We’ve all heard of DNA, it is that genetic code that every person has built into your body at the cellular level. In the past DNA testing was a very expensive process but recently the prices have come down considerably and several companies have appeared that specialize in DNA testing for genealogical purposes. These tests are very simple and painless.
How can it help with genealogy? There are several different types of tests. I’ll go over them one by one with the simplest explanations I can manage. These explanations will be overly simplified so won’t contain a lot of confusing scientific jargon.


Y-Chromosome Test used for Surname studies

Men have the Y-Chromosome. Women don't. When you take the Y-Chromosome test you get a list of numbers (markers) that identify your Y-Chromosome. These numbers are compared to others to see if you are related or not, or how closely you are related. Since only men have the Y-Chromosome there are certain things to keep in mind.

Your markers should match your father's perfectly (or nearly so). You should also match your brothers perfectly (or nearly so). You should also match your grandfather (your father's father), and his father (your great grandfather) and his father (your great great) and so on. Now since those older generations might not be around to test, you can't really compare your markers to theirs. However, you should know that your markers should be the same as those of your male, paternal ancestors back many generations. The value of this is in comparing to other living people.

Suppose you have a 1st cousin. Your father and his father are brothers. Your markers should match perfectly (or nearly so). That is no surprise. What about a more distant cousin, say a 2nd cousin? Your grandfather and his grandfather are brothers and you share the same surname. Your markers should be a strong match. The real value comes in comparing to a 3rd, 4th, 5th or even more distant cousin or someone you don't know even know if they are related or not.

Assuming that you and the other person both have the same surname, are both male, and have no "burps" in your lineage (adoptions, out of wedlock births, or anything of that sort that would skew the results), then you and he could find out if you have a common ancestor or not. If your markers match, then you probably have a common ancestor. If they don't match, then you aren't related on the paternal line via your common surname (you could be related some other way, but DNA testing won't tell you that).

Who Can I Compare to?

Anyone of your surname who is male. You might also find you match people of other surnames. That could be caused by a name change somewhere along the way (via adoption, etc.), or if the match is weak, but still a match, it may mean your common ancestor is so far back it pre-dates the common use of surnames. Those kind of matches are very hard to document via normal research.

Who Can't I Compare to?

Women can't use the Y-DNA test since they don't have a Y-Chromosome. However, a woman can use her nearest male relative of that surname as a surrogate to test on her behalf. That would be her brother, father, uncle or close cousin who has the same surname and an unbroken lineage.

You can't compare your results to people of other surnames, even if you know you are related to that surname. For example, you have a 1st cousin, he is male, but he is a child of your father's sister. You and he don't have the same surname and you won't have the same Y-Chromosome markers. He will have those of his father which will be different from yours since his father and your father aren't of the same lineage.

It is a paternal test, so it only works if you share a paternal ancestry.

What can mess up the test results?

Suppose you take the test and you don't match someone you think you should have matched. What can cause that? A couple of things come to mind:

  1. Your research has led you up the wrong tree, and you aren't really part of the family you thought. Either that or the other person isn't part of that tree but you are. More research may resolve it. It may also help to get other test participants to see which branch of the tree may be off.
  2. You or someone in your direct paternal lineage was adopted, and therefore your markers won't match your close kin, since they aren't blood relatives after all.
  3. Another possibility is an out of wedlock birth. One of your male paternal ancestors could have been born to an unmarried woman, and took her surname (as was generally required), and though you have the same surname, you won't match other family members beyond that generation. Your DNA markers will reflect those of the father, whether known or unknown.

The value of this test goes way beyond confirming relationships you already know (for example you and your brothers should all match, you and your male 1st cousins of your surname should match, etc.). The real value comes when someone’s results matches yours who’s connection to your family is not proven. If you share the same surname and have no non paternal events, then that normally means you do have a common direct male ancestor, even if your regular traditional research has not yet made the connection, genetically your relationship is proven. Now it is up to you to find the paper trail to tie it all together. It also helps when there is no match found, for then you know your line and the other persons are not related.

Which test should I take?

There are several test levels: 12 marker, 25 marker, 37 marker and 67 markers.  I believe the 12 and 25 marker tests are of little value. With those you may find you match half the planet, which isn't of much help. 37 or 67 markers are much better at narrowing down closer relations.

mtDNA test (Mitochondrial DNA) for your maternal ancestry.

Now, the Y-Chromosome test is only for males and only for your direct male lineage, your father, his father and his father’s father, and so forth. Are women left out completely? No. Read on.

The mtDNA test is similar to the Y-Chromosome test except that it is for females too and traces your direct maternal ancestry. mtDNA is handed down from mother to child (men and women, though men don't hand it down), so this test should show identical results for you, your mother, your mother’s mother, and so forth, back many generations. This is not real useful for surname studies unless you work it out to compare your results with someone else who shares your maternal ancestor of interest and descends in the same geometric way you do (female to female to female, all the way to the present). For example, say you are Ms. Smith (your maiden name), your mother was a Ms. Jones (maiden name), her mother was Ms. Thompson, and her mother was Ms. Johnson. If you take the test, and another direct female descendant of Ms. Johnson takes the test, you two should have matching results. Non paternal events won’t skew these results for it goes female to female and in most cases the mother is the mother (unless there was an adoption).


DNAPrint test results show which major population groups your ancestry comes from. This test is available for males and females. Your results will show you what major population groups make up the bulk of your ancestry over the past couple of hundred years. For example, my test might show these results:
Western European: 90%
Native American: 5%
African: 5%

There is a small percentage of error involved, and these tests are only good for a finite number of generations, so your results may not be what you expect.

For More Information

There are numerous places on the Internet that talk about DNA testing in various amounts of detail. Go to the source at and watch the video on this subject and get the current prices. Find out if a surname project is already in progress for your surname of interest.