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Archiver > GENEALOGY-DNA > 2001-01 > 0978983474


From:
Subject: [DNA] DNA from 8 great-grandparents
Date: Mon, 8 Jan 2001 14:51:14 EST


Back before Christmas, I received the following message from a lurker. I
thought it was a neat idea and raised some interesting issues for the whole
mailing list, so I'm quoting it here and opening the subject for discussion:

"I would like to get DNA outlines (for want of a better term) of each of my
eight great-grandparents. They are all deceased. I assume when it concerns
the great-grandmothers, I should get a sample from a direct straight-line
female descendant. Correct? How do I pick which descendant to use to get
the correct DNA outline from each of my great-grandfathers? I think I
would use Family Tree DNA which I believe has tests for both female and male
DNA."

Here is the way I analyzed the situation:

If you print out a 4-generation pedigree that labels the names with the
ahnehntafel numbering system, the skeleton would look something like this
(you may need to use a monospaced font for proper alignment):


|-8
|-4-|
| |-9
|-2-|
| | |-10
| |-5-|
| |-11
|
1-|
|
| |-12
| |-6-|
| | |-13
|-3-|
| |-14
|-7-|
|-15

In the ahnentafel numbering scheme, the father's number is always 2x the
child's number, and the mother's number is 2x the child's number + 1. If your
genealogy program doesn't use the numbers on a pedigree chart, you can pencil
them in yourself so you can follow this message with names from your own
pedigree.

Males are always even, and females are always odd (in the numerical sense, of
course!). If you keep dividing a person's ahnentafel number by two, you can
tell how the pedigree zigzags back and forth between males and females.

Now if #1 is a male, then a Y-line DNA test will take him back 1-2-4-8 and an
mtDNA test will take him back 1-3-7-15, so that takes care of two of the
eight great-grandparents.

#9 and #13 are great-grandmothers who had sons #4 and #6. So if you want to
know what the mtDNA of #9 and #13 was like, you will need to find OTHER
descendants in a straight line of females from them.

#11 is a great-grandmother who had a daughter #5, but then that daughter had
a son #2. So you can look for other descendants in a female line from #5 or
#11. Since you probably know more about #5 than #11, that could be easier.

Similarly, #10 and #14 are great-grandfathers who had daughters #5 and #7. If
you want to know what their Y-chromosomes were like, you would need to find
other descendants in a straight line of males from them. And #12 is a
great-grandfather who had a son #6 who had a daughter #3. If you want to see
what his Y-chromosome was like, you could find other descendants in a
straight line of males from #6 or #12.

The trouble with this scenario is that there may not be any descendants in a
straight male or female line. What if great-grandmother #9 had only sons?
Then you'll need to step back another generation to see if she had sisters
with descendants and try to bring them forward to the present day. This gets
harder and harder the more generations back you have to go, of course.

When you get to the living representative, it would make sense to use males
if possible, since it doesn't cost a whole lot more to test mtDNA and
Y-chromosomes at the same time. You may not be personally interested in both,
but you would be adding to the database for other people to find matches.

This is probably a different direction than most of us study our genealogy. I
was taught to "start with what you know and work backwards" from your parents
to your grandparents to your great-grandparents, etc.

Lately, I've been reversing this, starting with a distant ancestor and
following descendants forward, hoping for a straight line of females. It's
been an interesting learning experience. You never know if you're going to
come to a dead end before you reach a living relative! But along the way, you
are collecting information which might be invaluable to someone else who
can't bridge a gap coming from the other direction. And I've often found that
these collateral connections have interesting things to share, such as family
Bible records or pictures, even if they're the "wrong" sex for a DNA test.

I really do think that DNA testing opens up new avenues for traditional
genealogical research -- I'm certainly motivated to do more work on
collateral lines.

Everyone, please review my message and see if I've laid out the scenario
correctly, and add your thoughts, too.



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