Testing - A Scary Thing?
Absolutely not! DNA testing can be a very helpful genealogical research tool. Does
it tell you who your ancestors were and where they lived? No, but neither does anything
else that is in the public forum today, at least not with certainty. Do you have
a "brick-wall"? We have all come across one now and then. Y-DNA testing may be the
answer. For a quick lesson in DNA testing for genealogical purposes, let's go
here.
Genetic Genealogy
For Genetic Genealogy, which is the application of DNA testing to genealogy research,
two areas of DNA have shown to provide information that can be used in conjunction
with genealogy research. These two areas are the Y chromosome and mtDNA. These areas
of the Y chromosome and mtDNA do not contain information about a persons traits
or medical information. For example, the Y DNA area is known as Junk DNA by the
scientists, since it does not code for personal information.
Caveats
An individual's test results have little meaning on their own. You cannot take these
numbers, plug them into some formula and find out who your ancestors are. The value
of the test results depends on how your results compare to other test results. And
even when you match someone else, it will only indicate that you and the person
you match share a common ancestor. Depending on the number of markers tested and
the number of matches it will indicate with a certain degree of probability how
long ago this common ancestor existed. It will not show exactly who this ancestor
is. That must be investigated through traditional genealogical research.
The Y-Chromosome is passed from father to son. The vast majority of the time the
father passes an exact copy of his Y-Chromosome to his son. This means that the
markers of the son are identical to those of his father. However on rare occasion
there is a mutation or change in one of the markers. The change is either an insertion
or a deletion. An insertion is when an additional repeat is added to a marker. A
deletion is when one of the repeats is deleted.
Mutations occur at random. This means it is possible for two distant cousins to
match exactly on all markers while two brothers might not match exactly. Because
of the random nature of mutations we must use statistics and probability to estimate
the Time to the Most Recent Common Ancestor (TMRCA). The actual calculations of
TMRCA are mathematically complex and depend on knowing the rate of mutation and
the true number of mutations.