Hell Again!
Often people are confused with what DNA test to take for genealogy purposes. A basic
general primer can be seen at:
https://carpentercousins.com/DNATesting.pdf
Currently the most popular DNA test is the autosomal DNA (atDNA) test. Most people us it
for ethnic origins and some actually use it for genealogy purposes.
That atDNA test is excellent for immediate family and cousins. Once you start going back
to about 3 generations back in time, you begin to potentially lose cousin matching due to
the randomness of recombination at conception. Remember the 50% from each parent? This
means you do not have 50% of their atDNA from each parent.
Six generations into your past you get into the 1% range and into random matches. The
atDNA experts call this identical by state. It still sounds like the possibility of random
matches to me!
See the article and chart on theoretical probabilities at:
https://isogg.org/wiki/Cousin_statistics
See also the article and chart at:
https://isogg.org/wiki/Autosomal_DNA_statistics#Distribution_of_genealogi...
In general, atDNA testing is short range DNA. The farther back in time, it is less
effective.
Mitochondrial DNA (mtDNA) and Y-Chromosomal DNA (Y-DNA) does not have this short range
problem. While these types of DNA is passed down virtually unchanged over the generations,
there are the relatively rare random mutations. These actually can be helpful in
sub-grouping in some lineages.
The key to any DNA testing is knowing what you want to accomplish.
For immediate family and cousins = atDNA.
For descendants of a male ancestor and surname research = Y-DNA.
For confirming descent from a female ancestor = mtDNA.
Then watch the sales and save money!
John R. Carpenter
La Mesa, CA USA
Carpenter Cousins Project - Our main support page!
https://carpentercousins.com