|
To test if a Grandmother is related to a granddaughter
is very accurate using an X Chromosome DNA test.
All males have one X-chromosome that they have recieved
from their Mother. Subsequently, this single maternal
X chromosome is passed from father's to daughters. (Son's
receive a Y chromosome from their fathers).
So, by testing the two X chromosomes in a grandmother,
and the two X chromosomes in the granddaughter, we can
determine if they are biologically related by finding
if they both have one X chromsome exactly the same.
From the illustration left, you can see the flow of
X chromosome from Grandmother to Granddaughter, via
the father.
|