It is also possible, especially with a small block that you got 1/2 of the
matching block >from your mother and the other 1/2 >from your father making it
a false match, your match's match with your parents might not even show up
at FTDNA, which reports matches down to the 1 cM level (but does require a
min of 20 cMs with a longest block of at least 7). There is a lot of
discussion on the Jewish and General DNA groups on Facebook about how these
small segments generally indicate Identical by State (IBS) instead of
Identical by Descent (IBD) and all matches under 7 should be ignored.
Furthermore, in order to have much luck in finding out how you are related,
you really need at least two large segments - the larger over 30 and the
smaller over 10. Good luck to you.
Sarah L Meyer Christiansen
Georgetown, TX
https://sarahsgenies.com

---
From: Lynn Pollak Golumbic <lynnpollak@...>
Date: Tue, 13 Nov 2018 16:57:39 +0200

During the last year my parents (who are 3rd cousins) and I did the
autosomal family finder test on FTDNA. One surprise was that a very
good friend and neighbor with whom I thought I had no family
relationship came up as a 5th or remote cousin on my test, with 116
Shared Cm and a longest block of 9.
He did not show up on either of my parents' tests. Can someone explain
why? I am not adopted, I show up as a daughter of each of my parents.

On Nov 14, 2018, at 2:43 PM, Herbert I Lazerow lazer@... wrote:

My experience as a descendant of eastern European Jews is that if
your longest block of shared dna is 9 cMs, you are unlikely to be able
to prove a relationship between this neighbor because the records do
not go back far enough.

I do not disagree, although have a known Ashkenazic third cousin, with a
common ancestor born ca. 1825, whose longest shared block with me is 9 cM.

She is an outlier, and her brother's longest shared block with me is 15
cM, but still, I think it's worth keeping in mind.

David Brostoff

Lynn Pollak Golumbic wrote:

---
During the last year my parents (who are 3rd cousins) and I did the
autosomal family finder test on FTDNA. One surprise was that a very good
friend and neighbor with whom I thought I had no family relationship came up
as a 5th or remote cousin on my test, with 116 Shared Cm and a longest
block of 9.
He did not show up on either of my parents' tests. Can someone explain why?
I am not adopted, I show up as a daughter of each of my parents.
---

This is a consequence of Ashkenazi Jewish endogamy, the fact that we married
almost exclusively within our own population. We are all descended >from a
"founder" group of approximately 350 people who lived some 700 years ago.
For quite a few generations, Ashkenazi Jews married their first, second and
third cousins before the population's rapid growth in the 18th and 19th
centuries. As a consequence, we share lots of little bits and pieces of DNA

from way back. These common bits skew the autosomal analysis algorithms

because they look just like the shared DNA segments that signify
genealogically accessible relationships within the most recent four to five
generations. As a result, the majority of relationship estimates make the
common ancestors appear to be much closer than they actually are. We may be
projected as fourth cousins, but in reality we may be eighth to twentieth
cousins many times over because of the repeated endogamous marriages.

People listed in the results as fifth to distant cousins are almost always
very distant, out of reach of conventional genealogical research. There is
a "tell", however. The general rule of thumb that I've found most useful
(although not foolproof) is to investigate a match further if it contains
one segment of at least 20 cM and another segment of at least 10 cM.
Matches that don't meet this criterion are unlikely to yield an accessible
relationship. A long segment of only 9 cM is almost certainly a sign of no
common ancestor within reach. For matches that do pass this test, you may
or may not be able to connect your family trees, depending on how far back
your paper trail goes. I have one match with a 56 cM segment and a 20 cM
segment that I'm convinced is a third cousin of my dad, but we cannot
confirm such a relationship because I've been able to trace siblings of only
nine of my sixteen fourth generation ancestors, while my match doesn't trace
as far back.

Keep searching, and focus on matches that look promising. I have over
19,000 DNA matches on FTDNA, and I've been able to find some distant
cousins among them. I hope you'll enjoy similar successes.

---
David J Ellis
Natick, MA
djemkitso@...

Lynn,

During the last year my parents (who are 3rd cousins) and I did the
autosomal family finder test on FTDNA. One surprise was that a very
good friend and neighbor with whom I thought I had no family
relationship came up as a 5th or remote cousin on my test, with 116
Shared Cm and a longest block of 9.
He did not show up on either of my parents' tests. Can someone explain
why? I am not adopted, I show up as a daughter of each of my parents.>

My experience as a descendant of eastern European Jews is that if
your longest block of shared dna is 9 cMs, you are unlikely to be able
to prove a relationship between this neighbor because the records do
not go back far enough. If your ancestors were in western Europe or
the U.S. a long time ago, it is possible.
This dna tracing is a combination of science and statistics.
Either could be incorrect, and both are being refined as we speak and
as the testing services' databases become larger.
This is just a guess, but I think the explanation for the match
with you but with neither of your parents is this. Whatever dna you
share with this neighbor came about half >from your father and half

from your mother. The amount shared with neither of your parents was

enough statistically to get them over whatever threshhold of
relationship FT DNA has. Put together in you, it was enough.
Bert
--
Herbert Lazerow
San Diego CA

Hello,
If you both upload to GedMatch your own and your parent's results and
use the "Phase" tool at GedMatch, it will split your DNA into the maternal
and paternal "slices". This will allow you to eliminate many False
Positives. 9cm is very small. If your "sliced" DNA matches still, it
will tell you >from which side of yours and which side of your friend's
parents the match exists.

There are some very good articles on this. Try googling with these
words: dna gedmatch parental phasing

(I like Blaine's article and Roberta's too)

Moishe Miller
Brooklyn, NY
moishe.miller@...

During the last year my parents (who are 3rd cousins) and I did the
autosomal family finder test on FTDNA. One surprise was that a very
good friend and neighbor with whom I thought I had no family
relationship came up as a 5th or remote cousin on my test, with 116
Shared Cm and a longest block of 9.
He did not show up on either of my parents' tests. Can someone explain
why? I am not adopted, I show up as a daughter of each of my parents.
Many thanks,
Lynn Pollak Golumbic
Haifa