Which DNA relationships to confirm for maternal cousin

+10 votes
405 views

I share data on 23andMe with my second cousin Karl Sanders. Our maternal grandmothers were sisters. Karl and I share 141 cM across 9 matches, including our X chromosomes. We are both classified in mtDNA haplogroup U5a1a by 23andMe. 

This seems like a great confirmation of our family relationship. Karl doesn't participate on GEDmatch or Mitosearch, and we haven't shared raw data. I'm wondering how to best take advantage of the "confirmed with DNA" features here on WikiTree. Is it appropriate to confirm my relationship to my mother, hers to her mother, Karl's to his mother and hers to her mother without a publicly verifiable comparison? Or is it best to stay away from the confirmation tools for now?

WikiTree profile: Anna Daily
in Genealogy Help by Karen Lowe G2G6 Pilot (139k points)
Thank you for asking this question. I'm just now seeing other names aside from mine/my Dad's as having taken a DNA test on profiles of ancestors. I have no clue how to figure out if that makes any relationship "DNA confirmed". I have checked that DNA has confirmed that I'm my Dad's daughter :D

4 Answers

+3 votes
You need to have a triangulated group (three or more people that share the same segment on the same chromosome) and trace back to a common ancestor in order to confirm auDNA matches.  Are you on Gedmatch?  If so, start working your triangulated groups and hope that you come across others that trace back to the family you're seeking to confirm.  I've got multiple triangulated groups with more than 15 people in them; some of my ancestors have a lot of descendants that have taken auDNA tests!
by Darlene Athey-Hill G2G6 Pilot (428k points)
Darlene, if our families believed our grandmothers were sisters and shared maternal lineage, and if our mtDNA confirms a shared maternal lineage, and our auDNA confirms a close second cousin relationship, is this enough to add some DNA confirmation within these three generations?

My late brother and I are on GEDmatch (I've noted this in our profiles). My second cousin isn't there, but I can view our matches on 23andMe.
Karen, it seems pretty darn certain that you and your second cousin indeed share common great-grandparents.  I have two second cousins (one on Gedmatch and one on FTDNA) with whom I share a lot of DNA.  Fortunately I've got a LOT of people that have matched me and at least one other person farther up most of my great-grandparents' lines, so through triangulation I've proved the connection (even though with all the shared DNA it was obvious).

I personally see no harm in confirming both of you back to your shared great-grandparents, although I would note on the profiles of each generation exactly why you marked them as such.  Can you talk Karl into uploading to Gedmatch?  If not, since you can see the shared segments on 23andMe, you will eventually match others on Gedmatch on those segments and you can work with those people to confirm which families they're each from.  It's a huge help having close cousins test!

Have you thought about using DNAGedcom.com for analyzing your segments?  It's free to do so...
Darlene, I do plan to goind DNAGedcom. Unfortunately their 23andMe and FTDNA upload tools are down today, as is GEDmatch. :(

Yeah, they haven't allowed ftDNA for a long time; then they brought it up & took it down almost immediately.  I haven't updated ftDNA on there for almost three months.  As to Gedmatch, I noticed earlier they were down.  Hey, I'm just thankful these places exist.  They're excellent sites and free!  wink

+6 votes
There are draft instructions for this http://www.wikitree.com/wiki/DNA_Confirmation

Third cousins and closer do not necessarily need triangulated groups to use the confirmed with DNA status indicators, although obviously that is a much stronger confirmation if you do!
by Veronica Williams G2G6 Pilot (144k points)
+1 vote
Hello Karen,

Most people who I invite to upload to GEDmatch or MitoSearch do so.

Just to be clear,  persons who test autosomal DNA almost never share (i.e. send to each other) their raw DNA.  In GEDmatch, your cousins who match you on a segment only get to see where the segment starts and stops.  Very few people have the skill to determine the raw content of that segment.

The portion (HVR1&2) uploaded to MitoSearch almost never reveals any health related issues.

Sincerely,
by Peter Roberts G2G6 Pilot (552k points)
+3 votes

I would mark both the mother of (1) both you and your 2nd cousins profile, and (2) both of your maternal grandmothers.  23andme predictions of 2nd cousins are >99% accurate.

https://customercare.23andme.com/hc/en-us/articles/202907230-The-probability-of-detecting-different-types-of-cousins

This means you share the same 2 great grandparents. The only other genetic possibility is that the other 3 grandfather and grandmother pairs are possible. I presume the documentation also backs this up so your DNA results are consistent.

by Ken Sargent G2G6 Mach 5 (56.8k points)

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