Archive | 2025

My Newly Found Half Second Cousin Once Removed

Dec19

A few months ago, my family had a good DNA match (about 151 cm for my aunt) at 23andme to our Bavarian side. This was Mary, who had been adopted as a baby back in 1950 from a Munich orphanage. She knew her birth mother’s name but not her father’s. She had no other significant matches at 23andme besides my family, so we needed to get her into more DNA databases to figure this out.

Great Grandfather Benedict Reiner

I sent her an Ancestry kit I had on hand and ordered a MyHeritage kit for her as well. Germany does not have very many people who have tested their DNA so typically my matches on those lines are Americans with Bavarian ancestors. However, there are a few tested Germans at MyHeritage.

While we waited for the new test results, I had her upload her DNA to GEDmatch so I could compare her to my known German cousins there. To my surprise, she matched my half second cousin in Bavaria at 91 cM. This is a line I have not researched deeply. I was hoping she matched my grandmother’s other side which I have much more information on. Luckily I am in touch with that cousin’s granddaughter Katharina, who enjoys doing genealogy. We found each other on GENI because she is descended from my great grandfather Benedict Reiner via a different partner (click here for that story)

Benedict’s mother Anna Reiner had several partners and at least two husbands so my plan was to start by building the trees of her other descendants. Naturally I fired off an email to Katharina and asked her what she knew. She sent me quite a bit of information and got involved in helping. She said to me “Now I remember why genealogy brings me so much joy — it’s just so fascinating!” Sadly many of Anna’s children had died before reaching an age to have children themselves and only one had moved to Munich.

The Ancestry results came in and Mary had two good matches (167 cM and 160 cM) who did not match each other or me, although one had a whole family of testers, all matching. Next I copied the Bavarians from their trees into Mary’s tree and then built their trees further back. There were some surnames of interest ….

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Ancestry’s Updated Ancestral Origins

Oct13

Ancestry.com has just completed a major update to its DNA bio-ancestry predictions that has broken down European countries into many smaller areas. They have added 68 locales, mainly in Europe. French Canadians are no longer listed as France, now they are either Quebec or Acadia. They have also made four jewish groups from one: Central and Eastern Ashkenazi plus North African and East Mediterranean Sephardic. Almost all my Jewish friends have no Sephardic listed, giving the lie to some family stories. There are some interesting new categories like Germans in Russia and one combining both sides of the English Channel into a new category called Southeastern England & Northwestern Europe.

I am enjoying looking at the updated origins of many of the people I have helped. On the next page I will show images of the more interesting mixtures. Here is a classic North European mix of a Tenneseean with colonial roots.

I do recommmend scrolling down and clicking on the link to what has changed. Below is the image of how the predictions for our Tennesseean are different from last year. Notice that Germany has gone from 21% to 2%. Some of that must now be Denmark and some SE England & NW Europe.

While 1-2% could be a 4th or 5th grandparent, it could also be just noise or too far back to find. I have often told people not to worry about a 1% call as it is too small to be sure of. In my own case, I lost my 1% Finnish, which I actually thought was accurate because its location matches one of the two where my Norwegian American dad has Finnish, according to 23andme. Additionally, 23andme has my brother matching the other location. We have yet to find that Finnish 4th or further back grandparent, but we do match many Finnish people on those segments over at GEDmatch. Perhaps they just have some Norwegian. More on that in another blog post.

To quote my own blog post from 2020 comparing the origin predictions at each company “predicting the ethnicity for people of Northern European heritage like my brother and myself, is very hard to do accurately because there was so much mixing of those populations.” The book “Who We Are and How We Got Here” by geneticist David Reich makes that point well and goes into the details of what ancient DNA teaches us about European migrations and mixtures.

I found the explanatory Ancestry white paper (click here to read it) hard to understand, so I enlisted two different AI platforms to summarize it for me. A fun use of this technology. To be fair, after the quite technical many paragraph summary ChatGPT gave me, I wised up and asked Claude to summarize it in plain English. That went better. Here are a few take aways:

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23andMe Update

Sep25

23andMe is now owned by​ Anne Wojcicki’s new non-profit The 23andMe Research Institute. An email has gone out to all of us users (see next page) explaining this, which also makes it clear that the focus will be on discovering the health issues in our DNA. Click here for my previous post on 23andme explaining why ​Anne has this interest. 

While crowd sourcing DNA health issues is certainly a worthy cause, it is not the main interest for many of us. Most of my readers consider genetic genealogy a tool to find relatives and uncover family stories.

How the former chromosome browser at 23andme looked comparing a new match to me and my family

The feature I miss the most at 23andme is the chromosome browser that showed ​where my genome matched that of my relatives. Because I have collected an excel file of all my father’s matches with notations as to which I or my brother share, I could frequently tell which family line a new match belonged to,  even a one segment match with no clear relatives in common. ​ Click here for the blog post where I discuss this.

I no longer recommend testing at 23andme unless you want health results or are an adoptee and thus need to test everywhere.

The next page has the text of the email they have sent all of us users.

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Half Sister or Aunt?

Sep18

There are many stories about families where the baby of an unwed teen was passed off as her own mother’s child. A recent query in a FaceBook group asked whether DNA testing could tell whether her aunt, her mother’s much younger presumed sister, was one of those cases, so actually the asker’s half sister. The problem is that the amount of cM shared by those two relationships completely overlaps, roughly 1600-2000 with outliers (click here for the charts at DNApainter).

Known paternal half siblings at DNA-sci

Previously I collected data and studied segment sizes to see how to tell those relationships apart (click here), finding that paternal half siblings will share more larger segments than aunt/uncles. However in this particular case, maternal half siblings, the difference is less clear. Click here for the calculator at DNA-SCI that takes segment sizes into account by using the number of segments. When I tried using it with the numbers of a pair of known paternal half siblings, that calculator predicted that aunt or uncle was more likely (see image). So this approach will not give a clear answer.

A half sister will get half their DNA from their other parent. This will usually result in some close matches that are not shared.  On the other hand, an aunt’s close matches should all be shared with her niece, since they share the same ancestors, so looking at their “not in common” matches might work. The niece, however, is expected to have close matches from her other parent’s side. Here are some half sibling examples from the tool “Match Both or 1 of 2” on GEDmatch:

The kits that match only half sibling A0 and not A5

The kits that match only half sibling A5 and not A0

Notice that each half sibling has a match larger than 200 cM that is not shared with the other. If you have pro tools and access to both accounts on Ancestry, you can also look at this by comparing each person’s list and the matches in common. There is no automated way to do that there yet. Family Tree DNA has a “not in common with” feature, but no other company has it.

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The new clustering tool at Ancestry

Jul6

Ancestry has been rolling out its clustering feature this past week to those of us with a Pro Tools subscription. If you have it, there is a new button at the top of your list of matches with an icon that says “By Cluster.”

The purpose of clustering is to create an easy-to-use visual way of organizing DNA matches that are related to you and to each other. The graphic sorts the matches who share 65 cM to 1,300 cM with you into groups who also share at least 20 cM with each other. Each match is listed in the rows on the left as well as by initials at the top for each column. In a perfect world, you would get four colored boxes, like in the image below, where each box represents the line of one of your grandparents.

The image above has actually had the top box truncated and two additional boxes removed for illustration purposes. The left side would have the full name of the match while the top has just the initials.

Some matches will also have additional matching that does not fit the groupings. Those are shown in gray.The darker boxes on the diagonal are where the same person meets themself. Note that all the boxes, even the ones that are not colored, are clickable to show who the two people that intersect there are, with all the details of that match. Plus the names can be clicked to go to those match pages. Clicking a square brings up a box like in this image.


Below the diagram there is  a list of the clusters. Click on any one to see the members of that group. Notice that each member has all the information you would see about that person in your match list. Another nice feature is that you can add everyone in a cluster to a colored dot group by clicking on the “+ Add All” button.


While this sounds like a wonderful new tool, for many of us it needs the ability to specify the range to include in order to get the best boxes. Below is what a Jewish friend of mine gets; lots of clear small boxes, but everyone is related to everyone else outside of the clusters, except for her middle box. This is what endogamy looks like!

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