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Several million people around the world have taken a DNA test over the
past couple of decades. Millions more now submit a sample for testing
each year. Genetic scientists have been able to determine that, if two
people share a certain percentage of their DNA, they must be related.
Further, if they share around 50%, they must be full siblings.
Grandparents, aunts, uncles, nieces and nephews would share about 25% of
the same DNA while first cousins share about 12.5%. This can be carried
out to where a 5th cousin may share 0.05% of their DNA.
Of course, in determining an exact relationship between two people had
to take into account such things as the age of the individuals. For
instance, a person who shares about 25% of your DNA but is only 2 years
older than you father, is most likely an uncle and not your grandfather.
DNA testing companies will offer you the opportunity to get in touch
with other people in their database who are related to you. You must
first agree to allow your data to be available so that relatives may be
able to contact you. |
In
2024, I submitted a saliva sample to Ancestry.com to
have my DNA analyzed. The following is my very basic
understanding of genetics, the way these tests work and
how to use the results for genealogical research.
Needless to say, there have been many books written on
these subjects so it can be very complicated.
Deoxyribonucleic
acid (DNA) in our cells contains the genetic memory which passes all
manner of traits from one generation to the next in our genes. Half of
our DNA comes from our biological father and the other half from our
biological mother. Although that percentage does not change, the
specific factors in the DNA will be different from one child to another.
That is why each of us is a unique human being.
We
humans have about 20,000 genes and each of these has some type of
influence on a particular trait in our bodies. A certain combination
will result in brown hair or blue eyes or our height or whether we are
more or less susceptible to certain types of cancer. It has only been in
recent decades with expanded computing power that scientists have been
able to map the human genome and identify the nature of our DNA.
