Monday, March 26, 2012

Understanding DNA and Genealogy

There was a lot of buzz about DNA and Genealogy at the recent RootsTech conference. I found myself impressed. Just think, we can determine if we have the same ancestors, as another. It will become a way we find living relatives.

I decided to refer you to a recent article I have come across. It has basic information and more. I will copy a portion and give you a link to the full article.  

Two portions of our DNA are not combined with that of the other parent. The 23rd
chromosome, in the green box above, determines the sex of the individual. Two
X chromosomes produce a female and an X and a Y chromosome produce a
male. Women do not have a Y chromosome (otherwise they would be males) so
they cannot contribute a Y chromosome to male offspring. Given this scenario,
males inherit their father’s Y chromosome unmixed with the mother’s DNA, and
an X chromosome unmixed with their father’s DNA.

This inheritance pattern is what makes it possible for us to use the Y
chromosome to compare against other men of the same surname to see if they
share a common ancestor, because if they do, their Y chromosome DNA will
match, either exactly or nearly so.

Autosomal DNA, X chromosomal DNA and, in males, Y chromosomal DNA are
all found in the nucleus of a cell. A a fourth type of DNA call mitochondrial DNA,
or mtDNA for short, resides within cells but outside the cell’s nucleus.
Mitochondrial DNA packets are the cell’s powerhouse as they provide the entire
body with energy.

For both genders, mitochondria DNA is inherited only from the mother. Men
have their mother’s mtDNA, but do not pass it on to their offspring. Women have
their mother’s mtDNA and pass it to both their female and male offspring. Given
this scenario, women inherit their mother’s mtDNA unmixed with the father’s and
pass it on generation to generation from female to female. (Males carry their
mother’s mtDNA, but don’t pass it on.) This inheritance pattern is what makes it
possible for us to compare our mtDNA with that of others to determine whether
we share a common female ancestor.

DNA Testing for Genealogy - What Can It Do For You??

Paper courtesy of Roberta Estes,

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