Why so few matches? #dna


Cindy g
 

Over the years I have had 39 people people tested. Typically, the
matches run into the thousands if not tens of thousand. I have one
person whose test results found less than 100 matches. This was the Y
chromosome test. Can anyone explain why this might be? >from what he
has told me know about his family, he seems to come >from a Jewish
family. Would the fact that there are so few matches reflect on his
being Jewish?

Thanks,
Cindy Gallard
Denver


Bob Kosovsky
 

On Sun, 11 Nov 2018, Cindy Gallard <gallardc@gmail.com> asked:

I have one
person whose test results found less than 100 matches. This was the Y
chromosome test. Can anyone explain why this might be?
I heard a speech by Bennett Greenspan a couple of years ago in which he
said that certain haplogroups don't have wide distribution, and that he
didn't have an explanation for that. He mention my group - haplogroup I -
as well as others (I can't remember which). People in the audience
suggested reasons such as population massacres, disease, but Greenspan was
non-committal and said more research needs to be done.

Bob Kosovsky, New York City, seeking any and all permutations/locations of:
KASOVSKI/Y, KASOWSKI/Y, KOSOFSKY, KOSOVSKY, KOSOWSKY, KOSOW, KOSSOVE, etc.
Slutsk: DAVIDSON, GELFAND (also Sioux City, Iowa)
Klodawa: JARET, JARETSKY, JARECKI, KOLSKY/I; Skierniewice: PIFKO, PIWKO


Jeffrey Mark Paull
 

In response to Cindy Gallard's question, "Why so few matches?," there
is a very simple answer as to why the results of autosomal DNA tests
will virtually always show many more genetic matches than the results
of Y-DNA tests. It boils down to a genetic numbers game. Ancestry,
23and Me, or FTDNA autosomal DNA tests will identify genetic matches
from all of your genetic lines, while the Y-DNA test focuses on a single
genetic line only -- the patrilineal line.

As an example, an autosomal DNA match at the 5th cousin level descends
from a common 4th-great-grandparent, which could be >from any one of 64
different genetic ancestral lines, irrespective of whether that line is
maternal or paternal. A 6th cousin descends >from any one of 128
different ancestral lines, and so on. In contrast, all Y-DNA genetic
matches on an individual's match list descend >from a single patrilineal
line.

Another important factor is the relative number of people in the testing
database. Because there are so many more people who test their autosomal
DNA compared to the number who test their Y-DNA, the chances of finding
genetic matches are much greater in the larger autosomal DNA databases.

The combination of both of these factors accounts for the much higher
number of genetic matches that are seen on autosomal DNA genetic match
lists. Reporting less than 100 genetic matches is not uncommon for the
results of a Y-DNA test; I have seen cases where an individual had no
Y-DNA genetic matches reported at all.

All the Best,

Jeffrey Mark Paull

---
From: Cindy g <gallardc@gmail.com>
Date: Sun, 11 Nov 2018 16:10:13 -0700

Over the years I have had 39 people people tested. Typically, the matches run into the thousands if not tens of thousand. I have one person whose test results found less than 100 matches. This was the Y chromosome test. Can anyone explain why this might be?
...


David Brostoff
 

On Nov 12, 2018, at 2:21 PM, Jeffrey Mark Paull SaxKat@msn.com wrote:

The combination of both of these factors accounts for the much higher
number of genetic matches that are seen on autosomal DNA genetic match
lists. Reporting less than 100 genetic matches is not uncommon for the
results of a Y-DNA test; I have seen cases where an individual had no
Y-DNA genetic matches reported at all.
Yes -- as a point of reference, with FTDNA, I have over 19,040 autosomal
matches, but only 179 Y-DNA matches at the 12-marker level.

David Brostoff


Miller Judith <gmajudymiller@...>
 

I only have six matches on my cousin’s ydna. Greenspan told me years
ago I was lucky to be here as that haplogroup was very sparse, perhaps
due to pogroms or disease like black death.

Judith Miller


Arline and Sidney Sachs
 

To answer Cindy g question "Why so few matches?, the first thing when
working with the Y-DNA is most males' mutations are lost because they have
no males on their direct paternal line. All males and females are from
the same two persons, one male and one female, that lived most likely at
different times. They were not the only people living then, therefore all
of others had their direct lines died out. For example, if one third of
the males have no sons, than only half of them will have grandsons by
their paternal line. As an example, my grandfather had seven sons. They
have only 5 sons. >from them, I was the only one with sons, 3 of them.
from them I only have one grandson. If he does not have any, the paternal
line will be gone.

Secondly the Y-DNA testing used STRs to find matches. Almost all the
mutations on them are the kind that a STR either lose or gain one compete
repeat at a time. However, at very rare time it is not a single repeat
but a multiple repeats or even a partial repeat. Beside this there are
several other type of mutation that could happened. By looking a only a
few people it is impossible to tell what type of mutation occurred. That
the reason haplogroup projects are so useful. I have a cousin who family
history is Cohenim. He has zero matches at the 12 markers level, only 2
at genetic distance of 2 at the 25 level, and only 4 at genetic distance
of 4 at the 37 level. What happened is that on a single marker, he was
few repeats off >from that of the Cohenim Module Haplogroup. He, or his
father, grandfather, or earlier, had the mutation of multiple repeats,
thus no close matches since each repeat is counted as one genetic
distance.

Sidney Sachs
Lorton, VA, USA