FTDNA Family Finder Statistics

Discussions concerning Autosomal DNA.

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R1b-Z251 (L583+)
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PostPosted: Fri Dec 07, 2012 9:42 pm
I recall that the FTDNA home page used to list the number of Y-DNA, mtDNA, and Family Finder test results in their data base, but I can't seen to locate that information anymore. Does anyone know how many test kits are in Family Finder? I would also like to know how many of those might represent Ashkenazi testers. Even with FTDNA's matching formula supposedly limiting matches for endogamous populations, I still have a very large number of matches (over 1365 last time I checked). So I am wondering what percent of Ashkenazi Family Finder kits my matches represent. Anyone have a clue?
Avatar: My Paternal Great-Grandfather, Reb Nison Ben Moshe HaLevi (L21>DF13>Z251>L583)
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Posts: 42
Joined: Sat Nov 24, 2012 6:42 pm
Location: Salish Sea, USA
YDNA:
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J1c7a
PostPosted: Sat Dec 08, 2012 12:56 am
seferhabahir wrote:I recall that the FTDNA home page used to list the number of Y-DNA, mtDNA, and Family Finder test results in their data base, but I can't seen to locate that information anymore. Does anyone know how many test kits are in Family Finder? I would also like to know how many of those might represent Ashkenazi testers. Even with FTDNA's matching formula supposedly limiting matches for endogamous populations, I still have a very large number of matches (over 1365 last time I checked). So I am wondering what percent of Ashkenazi Family Finder kits my matches represent. Anyone have a clue?


Perhaps my memory is faulty and they never did list the Family Finder statistics? There certainly isn't anything about Family Finder on their current statistics page.
Avatar: My Paternal Great-Grandfather, Reb Nison Ben Moshe HaLevi (L21>DF13>Z251>L583)

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Joined: Wed Mar 28, 2012 7:07 am

YDNA:
R-YP431
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H5a1-T152C!
PostPosted: Sun Dec 09, 2012 7:33 am
If you go to mtDNA or yDNA, and click on "ancestral origin", you will find some statistics (how many tested in each country) - at least.
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Posts: 42
Joined: Sat Nov 24, 2012 6:42 pm
Location: Salish Sea, USA
YDNA:
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PostPosted: Tue Dec 18, 2012 10:01 pm
Here's another question. I am trying to find some chromosomal marker that would indicate probable cousins on one of my specific line. I have now identified about 35 cousins (out of about 1400 Family Finder matches) - some with a Y-DNA haplogroup relationship, and some with surname variation spellings to my ancestor in question - that all have a common piece of chromosomal DNA. The matching section is small (only shows up on the 1+ cM screen in the browser tool). How much of a chance is there that this piece (it's on chromosome 7) is a reliable marker for cousins that might be descended from a single specific line. Since the probable common ancestor in question is probably 6-10 generations ago, is this small matching piece across 35 different cousins meaningful as an IBD indicator?
Avatar: My Paternal Great-Grandfather, Reb Nison Ben Moshe HaLevi (L21>DF13>Z251>L583)
User avatar
Posts: 42
Joined: Sat Nov 24, 2012 6:42 pm
Location: Salish Sea, USA
YDNA:
R1b-Z251 (L583+)
MtDNA:
J1c7a
PostPosted: Sun Dec 23, 2012 8:15 am
seferhabahir wrote:Here's another question. I am trying to find some chromosomal marker that would indicate probable cousins on one of my specific line. I have now identified about 35 cousins (out of about 1400 Family Finder matches) - some with a Y-DNA haplogroup relationship, and some with surname variation spellings to my ancestor in question - that all have a common piece of chromosomal DNA. The matching section is small (only shows up on the 1+ cM screen in the browser tool). How much of a chance is there that this piece (it's on chromosome 7) is a reliable marker for cousins that might be descended from a single specific line. Since the probable common ancestor in question is probably 6-10 generations ago, is this small matching piece across 35 different cousins meaningful as an IBD indicator?


I am still struggling with this, and hoping one of the experts in this area can help me. There are probably more of my matches that have this segment, but I'm stopping at 45.

In a recently published paper, "Identity by Descent Between Distant Relatives: Detection and Applications," Annual Review of Genetics, Vol. 46: 617-633 (publication date December 2012), Sharon R. Browning and Brian L. Browning, there is this statement about patterns of IBD sharing:

"...Fifth cousins usually have no detectable IBD sharing, and when they do have IBD sharing it is usually composed of a single IBD segment with a mean length of 8.3 cM (8 Mb). Extrapolating further, individuals who have shared ancestry through a certain common ancestor 25 generations ago (with 50 meioses of separation) almost always share none of their genome identical by descent through that ancestor, but if they do have an IBD segment through that ancestor it will have a mean length of 2 cM (2 Mb)."

Almost all 45 "cousins" have at least one large IBD segment over 8 cM somewhere, and also share the small segment on chromosome 7. For almost all, the chromosome 7 shared length is between 1.47 cM and 2.31 cM, matching the paper's suggestions. A handful have larger lengths between 2.81 and 6.68 cM that encompass the smaller range. This set of individuals is not random, but drawn from Family Finder suggested remote cousins. My guess, therefore, is that these "cousins" are probably descended from a single ancestor. If I take the 25 generations statement at face value, then perhaps it is an ancestor that survived the Black Death and subsequent pogroms, or maybe migrated to Eastern Europe from Iran many generations ago (because the Y-DNA haplogroup relationship mentioned in my earlier post is that for five of them they are known R2a, not a common Y-DNA haplogroup for Eastern European Ashkenazim).
Avatar: My Paternal Great-Grandfather, Reb Nison Ben Moshe HaLevi (L21>DF13>Z251>L583)

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Joined: Thu Mar 15, 2012 1:14 am

YDNA:
R1b-Z12*
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I3b (FMS)
PostPosted: Mon Dec 24, 2012 3:05 am
seferhabahir wrote:
seferhabahir wrote:I recall that the FTDNA home page used to list the number of Y-DNA, mtDNA, and Family Finder test results in their data base, but I can't seen to locate that information anymore. Does anyone know how many test kits are in Family Finder? I would also like to know how many of those might represent Ashkenazi testers. Even with FTDNA's matching formula supposedly limiting matches for endogamous populations, I still have a very large number of matches (over 1365 last time I checked). So I am wondering what percent of Ashkenazi Family Finder kits my matches represent. Anyone have a clue?


Perhaps my memory is faulty and they never did list the Family Finder statistics? There certainly isn't anything about Family Finder on their current statistics page.


There was a page of stats, but it didn't include Family Finder.
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