DNA Randomness: Siblings

If you have been researching genetic genealogy for any length of time and I guess more so if you have also taken courses or attended webinars,  you have heard about the randomness of DNA as it pertains to autosomal DNA inheritance.  While we each get 50% of our DNA from our father and 50% from our mother,  the 50% that we get from each parent is not the same 50% when comparing to other siblings(unless you are comparing Identical Twins).  I have 4 full siblings, only one of which has tested.   Even with just one having tested I can see that is true in comparing our matches and the amounts she and I match them.  Our Mother has tested also, so I have phased kits created at GEDmatch using her results in comparison with mine and also phased kits comparing her results to my sister's results.  These are very useful.

Ancestry has a phase filter which you can use if one or both parents have also tested at AncestryDNA.  Since I only have one parent that was able to test, that tool lets me see a listing of matches who are also a match to my Mother.  Keep in mind the match range is similar to Shared Matches tool in that it only includes 4th cousin and closer matches---not Distant Cousins.  It would be nice if they could do a list of 4C or closer who DO NOT MATCH when there is only one parent who has tested.

The chart below compares my match list with that of my full sister.  I did not include our Mother's results for our maternal matches nor the matches of my daughter.  I may do that in a future post  Those covered are matches who Ancestry DNA estimated were in 3rd cousin range for at least me OR my sister.

The RED border is around those who were in my list at 3rd Cousin or above.
The VIOLET border is around those who were in my sister's list at 3rd Cousin level.who were ranked as 4th cousins by Ancestry in my list.

Average Difference 65 cM
Total-M(Marie)
Total-B(Becca)

Notes:  Both of our parents have Colonial American Ancestry.  Pretty much all of our ancestors were in the US before 1800.
Our Distant Cousin matches Start on:
Page 41 of 876 (Becca)---- 30 matches which are 3rd Cousin or closer
Page 38 of 908 (Marie)-----26 matches which are 3rd Cousin or closer
Marie:  1873 4th cousin or closer matches
Becca:  2007 4th cousin or closer matches

GEDmatch comparison:  Marie and Becca
Largest segment = 145.6 cM

Total of segments > 7 cM = 2,507.6 cM
51 matching segments
Estimated number of generations to MRCA = 1.3
Six of my matches that were estimated 3rd cousin were in the 4th cousin range for my sister.  Eight of my sister's matches that were estimated 3rd cousin were in the 4th cousin range for me. There was one match who was on the low end of a 3rd cousin match for my sister who was in my Distant Cousin match.



Ancestry's Cousin Categories
From the Hyperlinked "What does this mean?" in the Amount of Shared DNA info box





A bit confusing I guess as there is a gap between categories. I did check for ours that fell
in the gap(195 cM) and it was noted as a 3rd cousin.

AncestryDNA match category spread for my family's tests.

Mom's AncestryDNA matches include
2 children
1 granddaughter

2nd Cousin AncestryDNA category
(which includes some projected 1st-2nd cousins & 2nd-3rd cousins)
11 cousins--3 of which have uploaded to GEDmatch.com
AncestryDNA estimated shared cMs ranges from 623 cMs over 21 segments --235 cM over 9 segments
All are Paternal cousins except one--a known maternal 1C1R of the Acuff/Hale variety

3rd Cousin AncestryDNA category
39 cousins--6 of which have uploaded to GEDmatch.com
AncestryDNA estimated shared cMs ranges from 188 cMs over 9 segments-- 91 cMs over 5 segments

Subtracting those 50 matches and the 3 immediate family from her total shown 4th Cousins or closer match total and she has 2,266 4th cousins.  For the record all of Mom's 3rd cousins or closer have been asked if they would consider uploading their results to GEDmatch.  Looking at Mom's matches made me curious how the numbers compared to my results as well as those of my daughter, and my sister.

Mom is very fortunate to have many of  her closer cousins who have tested.  I wish more of the closer cousins would upload to GEDmatch.  It certainly would make sorting the matches easier.  In the end though it is their choice and more times than not, it is just not a priority for them.

Working AncestryDNA circles and a few observations

My sister and I have both tested at AncestryDNA.  When I am working on a segment and it is pointing in the direction of a specific ancestor, I always check my AncestryDNA circles to see if I have a Circle for that particular ancestor or ancestor couple.  I work the circles.  What do I mean by work?  I have a spreadsheet template I use.  I begin by adding the Ancestor's name at the top.  The spreadsheet has columns for:

• Ancestry User Name
• Match or Match to Circle
• Estimated cMs/segments
• Group(Child thru which they descend)
• GEDmatch #(known and added as they upload)

I add the info for each circle I work and this helps me to track not only who matches me but the descendant pathways.  Also and probably the most important thing for me is that I can see at a glance which tester would be the most valuable to have their info at GEDmatch.   I generally write those who Ancestry estimates match me on multiple segments or at amounts greater than 15 cMs.  I ask them to consider uploading to GEDmatch if they are not already there and if they have uploaded, how to identify them among my many matches.  I want to focus on these larger matches for a number of reasons. The circle membership gives me a pretty good idea of where they could match me. It is easy to get overwhelmed by all the matches but I feel if you focus on the larger ones, those will help in identifying others.   I also like to look at the smaller matches and see how their estimated segment matches are in comparison with my sister's results.  If they match her at amounts over 15cMs I also message them. 

Stay focused on the larger matches when trying to get folks to GEDmatch.  However do not forget the randomness of DNA.  Siblings can vary greatly in what matches they have.

My sister and I are a great example of that.

Since Mom tested I was able to make phased kits(thanks to GEDmatch tools) which show the matches that each of us got from Dad(who passed before we began DNA testing.)  I have compared my Paternal Phased Kit to my sister, Becca's Paternal Phased Kit and also compared each of our Maternal Phased Kits.   Below are the results

Comparing Paternal Phased for Marie and Paternal Phased for Becca(Full siblings)

(Chr 1-22, X not included)

Largest segment = 134.6 cM

Total of segments > 7 cM = 1,526.2 cM

33 matching segments

Estimated number of generations to MRCA = 1.6

Comparing Maternal Phased for Marie and Maternal Phased for Becca(Full siblings)

(Chr 1-22, X not included)

Largest segment = 145.6 cM

Total of segments > 7 cM = 2,513.8 cM

50 matching segments

Estimated number of generations to MRCA = 1.3

So you can see that on our Paternal lines we appear to have gotten a greater variety, while Mom seems to have given us more of the same.  

Table below shows another example of the randomness. The amounts shown are those estimated by Ancestry and they tend to be slightly higher at GEDmatch.

Comparing segment matches we have to
members of a Paternal Ancestor Circle.  

Shared Ancestor Hints are just that--Hints

I was extremely happy to get 14 new 4th cousins or closer matches on my AncestryDNA results overnight.  I wish people understood the importance of uploading to GEDmatch. Too many treat the circles or the DNA Hints as facts.  To them it is unnecessary to upload their raw data atDNA results to GEDmatch because Ancestry has told them the connection. Sure,  if you don't want to prove your research, go ahead and believe that!  Ancestry gives you hints and clues,  It is on you to investigate and research those.

I have the perfect example among my matches.  This match is kin to me on my Mom's side thru the Luna line at my 4th Great Grandparents.  She is not DNA kin to me or my Mother but she shows as DNA kin to my daughter and the Shared Ancestor Hint is my 4th Great Grandparents(my daughter's 5th Great Grandparents)  Clicking on the "i" shows that my daughter and this match have a shared estimated atDNA of 6.6 centiMorgans(cMs) shared across 1 DNA segment.

Ancestry has done a better job on their wording on the Shared Ancestor Hints than they did when they first appeared.  [If you want to learn more about hints & shared records watch Ancestry's Crista Cowan and her presentation, "Don't be a Searcher, be a Researcher" from RootsTech 2017.


What we should hear  "You have a 6th cousin through the Luna line of your maternal Grandmother with whom you share a 6.6 cM  portion of DNA across 1 segment.  It is possible that it may be through that Luna line. You need to investigate further"

Instead many people feel that they don't need to investigate further and take that info at face value whether it is through lack of understanding, laziness or just not really carrying to know the truth. I'm not talking about those that just tested to learn ethnicity and don't care to do more. I am fine with that.

Thankfully this match agreed to upload to GEDmatch.  Since both of my daughter's Paternal Grandparents have tested I was able to tell that the connection was through my daughter's Paternal Grandmother's lines.  I was also able to take it back a step further in finding where to look as my daughter's PGM's Mother(my daughter's Great Grandmother) had also tested.

The match amount at GEDmatch to:
Daughter:  11.3 cMs on 1 segment
Her  PGM:  12.4 cMs on 1 segment
Her PGM's Mom 12.6 cMs on 1 segment

I should also mention that while my Daughter tested at AncestryDNA, her PGM tested at 23&me and her Great Grandmother tested at FTDNA.  We can compare all of these test at GEDmatch.

I did run the One to One for this match against my results and my Moms and she didn't have any measurable DNA match with us.

Apparently it's Large Colonial Segment Week

I had a large 54 centiMorgans DNA segment(or chunk)  in Mom's matches that showed up just under a week ago.  Upon examining others who matched Mom and each other along the same segment I was able to determine it was likely from the Luna/Looney lines. All those that matched Mom along that segment have Robert Looney and Elizabeth Llewellyn as their most recent common ancestors.  This is my Mom's 5th Gr Grandparents and back a good ways.  That put Mom matching 6th cousins and several 6th cousins once removed at an amount (54cMs) that typically is indicative of 3rd cousins.   I am thinking that this has something to do with this couple  being from the Isle of Man or colonial.

Last night I found that I had a new match that AncestryDNA estimated matched me at 50 cMs shared on one segment.  The match is going to be on my Paternal side as he didn't match my Mom's test.  Upon checking this match with my sister's test I found that he matched her even better.  I think they probably share the same 50 cMs segment but they also share 4 other segments which I didn't get and match at 101 cMs over 5 segments.  It is entirely possible that they share 5 different segments which doesn't include the 50 cM segment that he and I share.  Shared matches appear to be somewhere along our PGM's Jakes/Morrow/Harger/Frizzell  lines--all colonial.  I can't wait to hear back from this match and hope to get them to upload to GEDmatch so I can identify the segments in my sister's file and make note that I got segments from our  PGF along the 4 which I don't have in common with my sister.

PGF= Paternal Grandfather
PGM=Paternal Grandmother

Focusing on Identifying higher cMs matching segments

I use GenomeMate Pro to help me keep track of my DNA matches and map my chromosomes.  Typically I import matches that are 7 centimorgans or more.  That can make for an overwhelming amount of matches especially given that most my paternal and maternal lines were in colonial America.  In GenomeMate Pro you can set preferences so that only matches over a certain amount will show while you are working them..and you can adjust this at any time.  I did have mine set at 12 cMs but still I was looking at an awful large amount of matches.  I've decided to set the option at 20 cms and work those and gradually lower the cM amount.  I started using this process yesterday and have identified 2 larger segment matches already.  Hopefully I'll have continued success using this strategy.  You can try this too if you are working your matches using GenomeMate Pro but you may need to make adjustments depending on how many matches and the avg cMs.  Twenty cMs just seems to work the best for me for now.

DNA To-Do List....the short version

• 2GCsof2GPs project
• Working the AncestryDNA circles
• Focusing on Identifying the larger matches