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View Full Version : Gedmatch question ? Relative or glitch?



Cyrianne
07-17-2016, 09:53 PM
If there's a gedmatch area, please move.

However, I am curious about something I noticed this morning when sorting through some stuff DNA wise using gedmatch.


This question involves one of the people on GEDmatch who has considerably higher autosomal or X dna match with myself & sibling compared to everyone else. Even greater than relatives I know share an Acadian / French Canadian background. As per X-DNA matrix he, as they are recorded as a male, have greater numbers [196.1, brother's % 73.3] versus my 58.5 shared with a full blooded sibling while the autosomal is 900 points almost greater [the autosomal matrix]. And the MRCA estimate puts at 1.0 versus 1.2 for myself/sibling.

The above is accessed through the GEDmatch option - People who match both kits.


It'd be easier to identify if the person had a name, but their profile is nameless & the email doesn't ring a bell. Nor, given the family, are many interested enough in the family roots to bother with DNA testing. I have one half sibling, but then she's a gal.


There's also the little fact that according to the one to one comparison we don't share any DNA with this chap. Either myself, or my sibling, from the generic unaltered threshold to lower thresholds nothing pops up. The one-to-many you can use the various tools [such as the segment matrix] and nothing shows there.

I believe inheritance & recombination may explain lack of segments depending on what one inherits. However, given so, expect some connection. The admixtures for example with a distant cousin I know I am still relatively the same. Myself - 40.65 North Altantic, cousin - 50.56 North Altantic, person 2.03 North Altantic. Myself - 6.17 East Med, cousin - 6.75 East Med, person - 33.45 east med, etc., etc., etc. for K13.

Haplogroups aren't the same, though interesting as both potentially confirms distant relatives were Jewish.



I guess what I am asking is, is this person really a relative or is it a potential glitch? I am asking as the kit is an M, 23&me, and there's been a close relative on 23&me that is likewise anonymous but there uncontactable for the last two years.

I'd like to get others options before sort of jumping feet first on the poor chap.

Cyrianne
07-19-2016, 08:53 AM
What no one has an option. A little help would be welcomed.

C J Wyatt III
07-19-2016, 01:00 PM
What no one has an option. A little help would be welcomed.

I am a little confused about what your are saying. A match of 196.1 cM on an 'X one-to-one' comparison is what you would expect with a mother-child or I believe a father-daughter pairing.

Jack

Cyrianne
07-19-2016, 04:55 PM
I am a little confused about what your are saying. A match of 196.1 cM on an 'X one-to-one' comparison is what you would expect with a mother-child or I believe a father-daughter pairing.

Jack

That's the thing. It is impossible to be either as neither of my parents have DNA tested. And I am definitely my parents' child for I have mum's facial features but have dad's build.

So who the heck or why the heck would an unknown person share so much DNA?

AJL
07-20-2016, 12:57 AM
There was a short-lived early version of the chip (now called V1) that had a much lower genotyping rate. Theoretically, someone could appear to match you because they have a long series of SNPs for which there is no call.

There are also some M-kits that are not living (or recently living) people but constructed from partial genomic information extracted from ancient remains. Often because of degradation there are lots of no-calls.

I'm not sure if something like this is happening.

anglesqueville
07-20-2016, 06:26 AM
Cyrianne, the same happened to my mother some months ago. An unknown person had appeared as the first line of her relatives' list, with a X-match greater than mine. There was panic. I decided to delete my mother's kit, and to upload it again. What I did. Since then the mysterious and impossible match has disappeared.

Cyrianne
07-20-2016, 11:01 AM
Cyrianne, the same happened to my mother some months ago. An unknown person had appeared as the first line of her relatives' list, with a X-match greater than mine. There was panic. I decided to delete my mother's kit, and to upload it again. What I did. Since then the mysterious and impossible match has disappeared.

Not panicking. It is just bizarre because there is an anonymous individual on 23&me who is quite a close relative, shares the most out of 1st cousins, and have never been capable of contacting him prior.

Does anyone think the intermarriage among colonist families & thus the DNA overlap [e.g. Acadians, as I continually get Acadian relatives closer by DNA than they are by paper trail] account for erroneously high DNA. This high seems ridiculous but still never know.

Mestace
07-21-2016, 07:23 AM
A scenario you can imagine, is someone tried to phase his result with the tool available on gedmatch and wrongly entered your kit number. Boum, huge match.