[ExI] 23andTriangulation

Henry Rivera hrivera at alumni.virginia.edu
Thu Jul 11 01:07:03 UTC 2013


Spike,

Since you can't seem to get unstuck from the genealogy topic, I will
chime in after all with no concern that I am encouraging you to
continue with this mostly non-extropian thread--we are way past that
point. Before there was 23andme, there was FamilyTreeDNA.com, of which
I am a member. My understanding is that 23andme does what they do but
adds the element of probabilities for certain medical conditions. On
FamilyTreeDNA, depending on what tests are ordered and the level of
specificity of markers used in those tests, one gets a list of
"matches" which updates as new members join and are found to be
related. Currently, they boast having the largest DNA database with a
total of 640,687records.

If one purchases a Y-DNA test, one will see matches sorted by genetic
"steps" with the headings Steps, Name, Test Ordered, Most Distant
Ancestor (as listed by the member), Y-DNA Haplogroup, Terminal SNP,
and Match Date. Each match has a TiP report link which reveals
probabilities that one shared a common ancestor with that member. For
example, on my top match, 2 steps away, I learn, "In comparing Y-DNA
37 marker results, the probability that USER X and Henry Rivera shared
a common ancestor within the last...

Generations Percentage
4                 31.08%
8                 71.35%
12               90.73%
16               97.39%
20               99.33%
24               99.84%"

So one learns there is a connection, but how distant a relative
remains somewhat vague. If one has a a family tree that goes back a
few generations, one can compare it with the match's family tree
looking for that common ancestor. Members can optionally post their
family trees in the form of GEDCOM files for matches to view/download
for this purpose. For some privacy, this disclaimer clarifies what one
can and cannot see in these family trees: "Move your mouse over a name
to see birth and death details if available. If a down arrow appears
over an individual's name, click on it to reveal more on that
particular line. Individuals known to be born within the past one
hundred years are hidden for privacy unless the GEDCOM owner specified
otherwise." I am not sure if you get similar data with 23andme, but
this sort of info helps with the triangulation you hope to accomplish
I think.

By the way, related to the initial thread on this topic, I am one of
those blokes who learned via DNA testing that I am not actually a
Rivera. While this did shake up my sense of identity for a moment, I
am glad I know this. I figured this out by connecting with some other
Riveras who are share common ancestors on my tree, and all were a
different haplogroup. It turns out my Rivera Y-DNA line has a known
and established haplogroup that doesn't doens't match mine. My top two
genetic matches have the surname Sena. I am probably a Sena. My
paternal great grandfather or one of his male ancestors, maybe a Sena,
managed to get raised by Riveras and took on the Rivera name. If it
happened knowingly, it was an adoption. If it happened
surreptitiously, a Rivera’s wife had an affair with a Sena man, and
their offspring was raised by the Rivera couple as their own.
Scandalous!

As more people do the DNA test, it may turn out I am not a Sena
either. I could better match with someone with a surname not yet in
the database. I also have common ancestors with these surnames in the
database: Rios, Santos, Lujan, Brito. Those common ancestors are
probably more than 16 generations out however.

Someone had to break it to me that it doesn't look like I'm a Rivera,
and I had to break the news to other relatives. Furthermore, I learned
that, based on my haplogroup, I am likely related to Sephartic Jews
who practiced in secret in New Mexico, even though I come from a
family of devout Roman Catholics! When I informed one of my aunts of
this, she responded, "Maybe you guys (referring to the other relatives
in the room) are Jewish, but I'm not!!" My grandmother who prayed the
rosary and went to mass daily would be turning in her grave if she
knew, I think. In the end, given the importance of this information, I
am glad to have stumbled upon it, and I think others on FamilyTreeDNA
and 23andme would feel the same way even if it is a surprise. That's
sort of why people do such DNA testing anyway, at least on
FamilyTreeDNA.

-Henry




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