When it comes to DNA, many of you, like me, might be scratching
your head and saying (to paraphrase Prissie in Gone with the Wind), “I
don’t know nothin’ ‘bout understandin’ no DNA.”
Boy, do I wish I would have taken time out from doodling and playing
cootie catcher to listen to at least a couple of my science teachers.
The University of Utah has put
together four short little videos explaining the four kinds of DNA – Autosomal DNA,
X Chromosome DNA, Y Chromosome DNA, and Mitochondrial DNA. Currently, three of these types of DNA - Autosomal,
YDNA and mtDNA (mitochondrial) are being used for genealogical purposes.
The type of DNA that Ancestry used
to predict my genetic ethnicity is autosomal.
If you are interested in understanding autosomal (a whole lot had better
than yours truly could hope to explain) take a peak now at U of U’s autosomal DNA video.
In a nutshell, each of us has 23
pairs of chromosomes. Autosomal DNA
looks at 22 of these pairs (the 23rd pair is the XY or XX
chromosomes that determine a person’s sex.)
You have inherited ½ your father’s
autosomal chromosomes and ½ of your mother’s autosomal chromosomes. But that also means that you lost half of each
of your parents’ autosomal chromosomes. Likewise, your parents only inherited ½ of
their parents’ autosomal chromosome etc.
This is why your siblings’ genetic
ethnicity might not look precisely the same as yours – they might have
inherited different chunks of your parents’ DNA. It’s also, why you and a cousin can take the
test and not come up a match, yet you and a fourth cousin are. It’s all in how the chromosomes recombined.
If you read the paper, “Melungeons, A Multi-Ethnic Population” by
Roberta J Estes, Jack H. Goins, Penny Ferguson and Janet Lewis Crain, you will
see that the prediction of how much of the DNA I probably carry from my 4th
great grandparents, Nimrod and Frances Thacker, is less than 1%. If you factor in the probability that the individual
who supplied the mixed race part of their DNA could have been 50, 100 or 200 years
prior to their births – well, you can see why my autosomal DNA might not have
picked it up.
For some of you who are
descendants of the Vinton County Group, you may have expanded your chances by
having several sets of the original group members. Only testing will tell.
Autosomal testing by Ancestry.com should be available to the
US market some time later this year. Family Tree DNA offers their own
product called Family Finder and 23 and
Me calls their product Relative Finder.
Note: As of right now, Ancestry does not offer the
option of looking at raw data, which the other products do.