| DNA is the blueprint from which your body is built. The DNA of all humans
is virtually identical and is the reason we have five fingers and toes and two
legs and arms. It determines where those parts are fastened to our body and
where our vital organs are placed. The very slight differences in our DNA determine
the slight differences we see in each other -- whether we're short or tall,
the color of our eyes and hair, the size of our feet, the shape of our sinuses,
tongue and voice box which determine how our voice sounds, etc. |
We use these slight differences to tell one another apart, and we use the
slight differences in our DNA to tell which family groups we belong to.
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There are three basic types of DNA
- Two of them are located within the nucleus of our cells:
- Autosomal DNA -- 22 pairs of rope-like chromosomes. This comes
from both parents.
- Y-chromosome DNA -- 1/2 of the 23rd pair of chromosomes. This
is passed from a father to his son.
- The third is located outside the cell's nucleus -- Mitochondrial DNA.
It comes only from the mother and is passed to her children.
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| We inherit random portions of our autosomal DNA from both of our parents,
whereas the Y-DNA and mtDNA come from only one parent. |
| In traditional research, we search for something unique that can be used
to define or identify an ancestor. A bunch of papers mixed together in a box
at the courthouse is meaningless without a name or place or some other tidbit
of information that we can use to help us in our research. |
| DNA is the same way. We need to be able to identify which parent contributed
it if it's to be used to trace ancestry. Autosomal DNA is like the mess of papers
in the box -- it has been randomly mixed up and we can't tell which parent contributed
it. It's of no use in genealogical work. On the other hand, mtDNA does not share
anything with the father's DNA, so it represents the mother's lineage. The Y-DNA
does not share anything with the mother's DNA and it represents the father's
line. The fact that these are passed unchanged from parent to child make them
ideal for tracing ancestry. The slight changes which occur when a mistake is
made in copying the DNA from parent to child become the distinguishing characteristics
for family branches. |
| Unfortunately mtDNA changes too slowly to provide very much useful data
for tracking recent ancestors. It is better suited to researching ancient ancestral
ties. Y-DNA changes more rapidly and has become the standard vehicle for genealogical
DNA research. |
