Research by Subject: Genealogy
DNA & Genealogy
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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
o
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.