I made up a new acronym! MDIDS

One of the fun things about managing your DNA matches in a spreadsheet is that you can choose to log whatever matters to you. I just added a new column to mine, and I invented a new acronym to go with it! It’s MDIDS (I pronounce it M-dids); and I use it alongside MRCA (Most Recent Common Ancestor), because sometimes MRCA isn’t quite what I want.



Let’s look at some examples. I’ll start with one that works just fine with MRCA. I share multiple segments with my 2nd cousin RS. Our grandfathers were brothers. We both descend from the parents of those brothers: JTT Hammond and Jessie Mary Griffith. So I put Hammond-Griffith in the MRCA column on any segment where I match RS. Easy-peasy. See image 1.

Image 1.

image 1 Aug 2017 post

But there are three or four situations where MRCA isn’t as effective for me.

Situation A. I think I’ve found a group of siblings whose descendants all share identical pieces of DNA, but I don’t know their parents.

For example, Elizabeth (Jennings) Griffith is one of my brick walls. I don’t have any documentary evidence leading to her parents. But several of her descendants have good DNA matching segments (over 15 cm) with descendants of four different Jennings men who all lived in Tuscarawas County, Ohio, the same time Elizabeth did. Like her, they were all born in Virginia between 1780 and 1800. Some of them appear on the same census page as Elizabeth; they were close neighbors in 1830. Given that I even have some triangulating segments, I’m pretty confident they’re her brothers. I believe the piece of DNA I have that matches those Jennings men’s descendants came to me from Elizabeth.

So now, I have an MDIDS column: Most Distant Identified DNA Source. I put Elizabeth in my MDIDS column, and ? Jennings-unknown in the MRCA column. I also like to add the ahnentafel number in my MDIDS entry, so I can tell at a glance how we’re related.1  Elizabeth is #105 in my ahnentafel, so now my spreadsheet entry looks like this. (See image 2.)

Image 2.

image 2 Aug 2017

Situation B. I match people who are descended from a different spouse of the same man.

For example, I’m descended from Benjamin Gorsuch and his first wife Nancy. I match cousins who descend from Ben and his second wife Susan. We don’t know Ben’s parents. I don’t want to put Ben and Nancy in my MRCA column, because that suggests that the DNA segment comes from either Ben or Nancy–I know it came from Ben, because it matches Ben’s descendants with his second wife. But just putting ? Gorsuch-unknown in the MRCA column feels a little inadequate. After all, if my tree went back a few more generations, I would have lots of ? Gorsuch-unknown entries in it. So I add 106-Benj Gorsuch in my MDIDS column. Ben is my Most Distant Identified DNA Source for that segment.

(Note: just like in situation A, I tend not to put distant ancestors in my MDIDS or MRCA columns unless I have triangulation or lots of matches to suggest the DNA really came from here and not some other ancestor in a line I maybe haven’t completed back that far.)

Situation C. I know which grandparent my segment comes from, because I don’t match a sibling there who has a good DNA match with a cousin related via the other grandparent.

For example, my brother B has a terrific (60cM!) segment with a 3rd cousin BJ on my dad’s dad’s side. I don’t match them there. Now, I know my dad had two copies of chromosome 8: one from Granddad and one from Nana.  If my brother’s chromosome 8 segment between 69 Mbp and 130 Mbp matches a cousin on Granddad’s side, and I don’t match them there, then that segment of DNA in my chromosome 8 must have come from Nana.2

Putting a MRCA on this segment in my chromosome map feels a little wrong, at least semantically, because MRCA stands for Most Recent Common Ancestor, and I haven’t actually identified any matches in common with me there. But I am confident that the Most Distant Identified DNA Source for that segment on my paternal copy of chromosome 8 is 005-Nana. So I put that info in my MDIDS column. See Image 3. (I haven’t decided yet if I want to enter something in the MRCA column in this case or not.)

Image 3.

Image 3 Aug 2017

Situation D. Visual Phasing is an advanced methodology that involves comparing the DNA of three or more siblings to identify crossover points and determine which grandparents contributed which DNA segments.3 Through visual phasing, I have assigned segments on a handful of chromosomes so far to specific grandparents. It’s very rewarding, but also very challenging and time-consuming!

Like situation C, I don’t necessarily have some cousin I match on these identified segments, with whom to have a ‘common ancestor’.  So I leave MRCA blank for now, but fill in the MDIDS with the grandparent I’ve identified, just like the previous example.

Tip if using MDIDS with Kitty Cooper’s Ancestor Chromosome Mapper

One hiccup to using MDIDS occurs when I want to use Kitty Cooper’s amazing Ancestor Chromosome Mapping tool to visualize which ancestors contributed which DNA segments.4 When I save a copy of my spreadsheet for this purpose, I only save these columns: | side | chr | Start | End | cMs | MDIDS | and optionally, Color. Then I sort by MDIDS. (Since mine all have 3-digit ahnentafel numbers, the tool will display those ancestors sorted from most recent to furthest back. Just my personal preference.) Next I rename the MDIDS column header in this draft spreadsheet to MRCA, because Kitty’s program looks for ‘MRCA’ to find the text data to display, although the term MRCA doesn’t appear on the resulting map. Finally, I save this version as a CSV file and upload it to Kitty’s tool. And voilà! (See Image 4.)

Image 4.

Aug chrom map

You’ll notice, besides the 3-digit ahnentafel number and name, I like to put the ancestor’s birth and death years in my MDIDS entry. And I include MDIDS for every segment I can map, even if I have a useful MRCA too. As mentioned at the beginning of this blog, a cool thing about these spreadsheets is that we can store whatever data we want. For example, I could just put a place like Ireland instead of a name if I wanted.

Add a column for GEDmatch kit numbers? Check. Date of your last correspondence with your match? Sure. MDIDS as well as MRCA? Why not?

How we manage our DNA data is up to us!

Ann Raymont © 2017


1. “Genealogical Numbering Systems,” Wikipedia (https://en.wikipedia.org/wiki/Genealogical_numbering_systems : accessed 4 Aug 2017.)

2. For more explanation of using siblings who don’t match on a segment to determine which grandparent the segment came from, see for example Ann Raymont, “Negative Evidence – autosomal DNA,” DNASleuth (https://dnasleuth.wordpress.com/2017/06/07/negative-evidence-autosomal-dna/ : accessed 4 Aug 2017.)

3. For more information on visual phasing, check out the links on the relevant ISOGGwiki page: “Visual Phasing,” ISOGGwiki (https://isogg.org/wiki/Visual_phasing : accessed 4 Aug 2017.)

4. Kitty Cooper, “Ancestor Chromosome Mapper,” Kitty Cooper’s Blog (http://blog.kittycooper.com/tools/my-graphing-or-mapping-tools/chromosome-mapper/ : accessed 4 Aug 2017.)



3 thoughts on “I made up a new acronym! MDIDS

  1. Sue Griffith

    Great minds think alike. I’ve been doing exactly the same thing (including Ahnentafel numbers and years on the chromosome map), rather than using an ancestral couple. I just hadn’t thought to give my MDIDS a name.

    Liked by 2 people

  2. jackalgq

    Ann I continue to say… You are brilliant! Our minds work alike but you are better at deciphering and explaining in simple terms what my mind is thinking! Hahaha. I’ve been trying to wrap my head around the inefficiencies with MRCA for a while and I think your MDIDS™ just did the trick! 🙂 Many of your examples make sense. A DNA cousin and I were having a conversation this morning and finding this blog is just the supplement we needed to move forward in the search for our connection. Thank you for your hard work and desire to spread your knowledge with the world!


  3. Pingback: Giving Thanks (DNA Painter) | DNAsleuth

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