Tuesday 31 March 2020

Tree completeness/genetic confirmation

Covid-19 has a lot to answer for but one good thing is that we can work around the unexpected limitations imposed.
The DNA Discovery 2020 tour of New Zealand by Blaine Bettinger and Angie Bush could no longer take place, but thanks to the organisers, and of course the presenters, who are in widely different timezones from us, and each other, the 2 day set of lectures were changed to online sessions.
From a participant viewpoint, everything worked smoothly and well - thank you all, Blaine, Angie, Michelle, Fiona and Paul.

Blaine's talk on new tools for DNA analysis, reminded me I was going to check out the new DNAPainter haplogroup functionality (see eight ways you can use ancestral trees at DNAPainter) and also to see if I'd made any progress on both my tree completeness, particularly which levels had now been validated by genetic matches.

Posts such as these encourage me to actually review progress, and what I'm trying to achieve.
It's good to have snapshots of where I was in a point in time when I get discouraged about lack of progress - which is, I admit, rare as this is all so much fun.

Spoiler alert:
I've apparently made some progress 😀


Before
After

The haplogroup progress will be a separate blogpost, as will the exploration of my supposed French-German ancestry (Yes Blaine, you inspired me to give biogeographical estimates another look and reminded me I was vaguely curious when I first looked at the segments 23andme identified years ago - it will be interesting to see what FTDNA comes up with in their promised equivalent).
On this page:

Tree completeness

For reminders of why names on trees and a few DNA matches is just a small part of the store front window of tree completeness read Blaine's blog post https://thegeneticgenealogist.com/2016/12/17/the-dna-era-of-genealogy/
Also Judy Russell's (thelegalgenealogist) on Filling in the Blanks

I've had a GEDCOM on DNAPainter since the beta tree functionality was announced, which means that two of my DNA-fuelled breakthroughs were already included in the tree.
The Lazy Vicar where the DNA leads/research had added parents and grandparents to my 2* great grandmother, so that was another branch complete to 4* greats.
I do so love a mystery or three likewise had added a whole 2 more ancestors to the level of 3* great grandparents, which of course only leaves more brickwalls to solve.

But what had not been included, given it only occurred in the last month was the review of my 3*great grandmother Jemima Parker's origins (Sarah not Charlotte; DNA strikes again refers).
So although she already had parents in my tree the tree has shrunk by one at that level (Jemima being the baseborn child of Sarah Parker) but grown by 4 more for her newfound mother's ancestry
Admittedly the link could still be somewhere back up from Jemima's husband, William Clinton about whom we know nothing beyond his marriage information and name on the baptismal records for their children.
Checking which is where the haplogroup confirmation can come to the fore - IF I can find a mitochondrial DNA descendant of Sarah Parker. There's only one found to date on paper, but not yet in person, and his surname is rather difficult for web searching - Wedding. But that's for the forthcoming haplogroup functionality post.

So with those added into my tree clicking on the highlighted Tree completeness link
gave me this table of how many ancestors I had at each level, and tells me about any ancestors who appear more than once (Pedigree collapse)


as you can see my tree completeness starts falling apart at the 4* great grandparent level and rapidly drops off after that.
One assumption at the 4th great level, not included here, would add 1 more at 4th, and 2 more at each of 5th and 6th great grandparent levels, all of which have interesting clusters of atDNA matches under active investigation - but given the stats on DNA inheritance at these levels the odds are fairly slim for making quick progress. I have however included the names in the surname hints/clues spot on DNAPainter.

The average amount of atDNA an individual can inherit from a specific ancestor halves as each generation passes, which does not necessarily mean that you will have inherited any from your btickwall one - but another cousin might have.
Encourage cousins to test, particularly those in the older generations still around on any of the lines of active investigation.
They beat your odds of not inheriting the crucial bit of DNA that will demolish the brickwall.

Check out the tables on the ISOGG WIki for the stats
- https://isogg.org/wiki/Autosomal_DNA_statistics and
- the theoretical probabilities https://isogg.org/wiki/Cousin_statistics
So it could take me some time to confirm the above assumption given the clusters of matches share a couple who married in 1738 and are, hopefully, my 5*great grandparents.
That's 8 generations (starting with me as the 1st) from whom, anyone in my generation can only expect to inherit 0.024% from one of those 5*great grandparents.
The likelihood of sharing significant matches with a 6th cousin is small, but possible.
Take comfort from the reported relationships with detectable matches at 6C and beyond in the Shared cMs project v4 also on DNAPainter.

Genetic confirmation

My first attempt at documenting which ancestors I'd confirmed at the time I started to pop this in DNAPainter resulted in the full fan tree view:

 shrinking to only this many being confirmed genetic ancestors:

which rather reflects my getting side-tracked rather than lack of confirmations, or I hope it does.

I admit I tend to work more on documenting the confirmations on WikiTree which pops dinky little symbols against each ancestor marked as "confirmed by DNA" (see WikiTree help for the WikiTree definition of / requirements for Confirmed by DNA status).
But the presentation there is by no means as compact - nor as colourful :)
eg

is just a portion of my WikiTree "compact" tree view (see https://www.WikiTree.com/treewidget/Henderson-2297/5 for all lines of the 8 generations available.)
This portion shows the newly changed parentage for Jemima Parker and reminds me I've not documented the confirmation back to Sarah Parker a fully triangulated DNA match thanks to my maternal aunts, a 2nd cousin, and a 4th cousin who all share with several descendants of Sarah Parker's later marriage.
Additional shared match networks exist with other descendants and also corroborate that another family is also connected somehow which research is yet to unearth - see my Clinton - Parker brickwall page on WkiTree

So what does the genetic tree look like after some quick work?

My use of confirmation differs between the two sites (DNAPainter and WikiTree).
On the DNAPainter tree I use "Genetic ancestor" check box

to show the Ancestral Couple that a match and I share out to 4th cousins, even where I may not have fully confirmed which of the couple any DNA segments come from.
This differs from WikiTree confirmation in that the latter is strict on identification only of the individual relationship that has been "proven", particularly once you get beyond 3rd cousins.
The same quandary of which to show exists when painting your chromosome maps.
You have to decide whether to show the ancestral couple you share, or the person one generation below that the DNA match has now confirmed gave you that bit of DNA.
Depending on whose map I'm working on, I tend to use which specific ancestor gave me/them that bit of DNA - but it sometimes gives me the feeling I'm not making much progress back up the generations given it stops one earlier. 😒


Thank you to Jonny Perl for DNAPainter, and the DNA Discovery 2020 team for making me actually stop exploring matches and do an overdue stock take.

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