Hi - They had a very good segment on this on 60 Minutes last night.
They explained how the # of grandparents expands so exponentially - if you
go back 8 generations, you have 256 grandparents, and 20 was something like
a million. And how this type of testing will prove a link to two of
them...and I think that was if you did one male and one female test.
Somebody on another list I'm on posted the link to the video:
Barb
The PBS Channnel http://www.pbs.org has several very good videos on DNA ...
In fact they have over 800+ when I searched "DNA video" ...
One need not go back too many generations to have more ancestors than there were people,
Hence, in your ancestry chart and mine, after some number of generations, most persons will have to be entered more than once. It represents cousins marrying cousins, not necessarily close cousins.
It is called 'pedigree collapse.'
Bob Doerr in the beautiful Missouri Ozarks
Sole surviving founding officer, Missouri Chapter, Nature Conservancy, 1956
http://www.nature.org/wherewework/northamerica/states/missouri/
Editor, since 1992, Missouri State Genealogical Association Journal
Barb,
Thanks for that link,
Barney