Friday, November 6, 2015

Updates to My AncestryDNA Results, and New Shared cM Feature

I haven't updated my AncestryDNA results in a blog post for some time, and there have been some important changes to the site, and to my matches.

There were two interesting blog posts today about the Shared centiMorgans that can now be found in a person's matches.  They were:

*  Exploring the New DNA Feature: Total cMs by Kitty Cooper on Kitty Cooper's Blog.

*  Ancestry's New "Amount of Shared DNA" -- What Does it Really Mean? by Roberta J. Estes on the DNAeXplained -- Genetic Genealogy blog.

Here are screen shots of my DNA Results Summary page:

The important information for me is that:

*  I have 81 Shared Ancestor Hints - these are autosomal DNA matches with common ancestors in their tree and my tree.

*  I have 131 4th cousins or closer - these are autosomal DNA matches, including those with shared Hints.

*  I have almost 4,500 matches with at least 5.0 in shared centiMorgans, but only 81 have a tree with a shared common ancestor.  About 10% of my matches don't have a tree or have a Private tree.

*  I now have five DNA Circles - for James Richman (1821-1912), his wife Hannah Rich (1824-1911), John Rich (1791-1868), his wife Rebecca Hill (1790-1862), and Zachariah Hildreth (1754-1828).  There are the same five matching persons in the Richman, Rich, Rich and Hill DNA Circles - we are all descendants of these persons.  There are four matching persons in the Hildreth DNA Circle, but I share enough autosomal DNA with one of them - but he shares enough with the other two.

*  I have no New Ancestor Discoveries yet (which is OK with me, since most of them I've heard about are erroneous).

What about the new feature - the Shared centiMorgans (cM) for AncestryDNA matches?  How do you find these?

Well, you click on one of your AncestryDNA matches.  Below the person's name is the "Predicted relationship: xxx Cousins" with a possible relationship range, and a Confidence level.  Beside the Confidence level is an icon with an "i" in a black circle - if the user clicks on that, they can see the "Amount of Shared DNA."

In the case above, I hare 91 cM across 8 DNA segments with this 4th cousin (we both have John Rich and Rebecca Hill in our trees as 3rd great-grandparents).

In the "Amount of Shared DNA" box above, there is a link for "What does this mean?"  When the user clicks that, a popup appears with information about shared DNA and confidence levels.  Here is the chart that defines the Confidence Level information, including the range of shared cM:

The shared cM information is helpful to understand the closeness of the relationships.

For the shared cM of 91 that I have with the DNA match above, the expected "Extremely high" confidence level is "above 30 centiMorgans" so that makes sense, although the match is a 4th cousin.
The "best" match I have on AncestryDNA is a second cousin (common great-grandparents), with 244 centiMorgans across 16 DNA segments.

The second best match I have is the example above with 91 centiMorgans in common across 8 DNA segments.

The third best match I have is a third cousin (common 2nd great-grandparents) with 76 centiMorgans across 6 DNA segments.

*  The fourth best match I have is a 4th cousin once removed (common ancestors are my 3rd great-grandparents) with 77 centiMorgans across 3 DNA segments.  We are also 5th cousins once removed (common ancestors are my 4th great-grandparents).

*  The fifth best match I have is a 2nd cousin twice removed (common ancestors are my great-grandparents) with 68 centiMorgans across 4 DNA segments.  This is a grandchild of my best match with 244 centiMorgans.

*  The sixth best match I have is a 3rd cousin (common 2nd great-grandparents) with 37 centiMorgans across 4 DNA segments.

The point here is that the amount of shared DNA can be highly variable - my 4th cousin match with 91 cM has much more shared DNA with me than my 3rd cousin with only 37 cM.

I can now add the amount of shared autosomal DNA CentiMorgans to my spreadsheet of AncestryDNA relatives, which includes the common ancestors and actual relationships (from research).

Of course, AncestryDNA still doesn't provide a chromosome browser wherein a user can see which chromosomes have the shared DNA.  AncestryDNA users need to use a third-party utility like GEDMatch in order to determine on which chromosome the shared DNA segments are located.  

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Copyright (c) 2015, Randall J. Seaver

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