Research by Subject: Genealogy

   DNA & Genealogy

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                         General OverviewWhat You Can ExpectHow to Begin


    Keep in mind that this is a new science.  What is true today may be different with new discovery.

    There are competing factors and priorities in DNA testing. 

          Some companies are primarily interested in "deep genealogy"
                     - tracking the human genome by increasing data for science to use
          Some companies are primarily interested in profits.  They sell tests and they often over-sell what
          can actually be learned by those tests.

          Some companies genuinely want to make science and genealogy work together but in many
          cases the people running things do not have enough genealogy experience to realize what
          is valuable to making the study really work.  They are so focused on the DNA / science side that
          they ignore the other half of genealogy which is the research that finds the documents and story. 

How DNA testing for Genealogists works.

The DNA that is tested is often referred to as "junk DNA."  A more precise description is "noncoding" DNA. 

Some scientists suggest you think of the strand of DNA like a television show During the show there is a break in programming for a commercial  These breaks are not the part of our DNA material that give coded information (such as your medical history or medical future). 

There may more to discover about the purpose of "junk DNA" but for now one of its primary interests has to do with our past.  It carries the story of of our lines for thousands of years.


In the center of the nucleus are long strands of DNA we call chromosomes

We get two sets chromosomes.  One set of 23 pairs from Mom.  One set of 23 pair from Dad.  46 Total. Every cell in our bodies has these in its nucleus.

Pairs 1-22 are called autosomal chromosomes.    (Autosomal DNA is used for paternity tests and forensics)

Pair 23 give us our XY Chromosomes

Men carry XY     Women carry XX 

Your mother can only give you her X chromosome.  Your dad can pass along his X (which makes you female) or his Y (which makes you male)

For chromosomes to be passed on they must be first be duplicated.  This takes place in your individual parent's cells. 

Y-DNA  (paternal)

DNA "unzips" and replicates itself.  If it didn't do a good job at this we might be born with three arms etc. 

It usually does the proper job but  Y-DNA often has slight copying changes.  For genetic genealogists these are known as MARKERS and help identify that you are more closely related to Frederick rather William.

Y-DNA is taken from the DNA in the nucleus of the cell


Mt-DNA (Mitrochondrial)  (my-toe-CON-dree-uhl) - maternal




MtDNA changes very slowly and does not provide so many changes in markers as Y-DNA.  For this reason your MtDNA test may show an exact match with a woman in Cincinnati but you can't tell if your common female ancestor was three generations ago or hundreds of years ago.

That lack of change makes it wonderful for following a line of women for thousands of years, or proving that the kidnapped daughter who is now 80 years old really is the same person.  It is the kind of test used by the military to identify remains during times of war.  It CAN tell you that you are related to another family.  It cannot tell you HOW or WHEN.