Visualizing Recombination and Segment Loss

I posted a graphic online yesterday showing chromosome paintings for three generations, from a grandmother to her son to her grandson. I think these types of graphics are very interesting, but I shared this particular graphic because it – rather dramatically, I think – shows the loss of numerous African and Native American segments through just those three generations.

The grandmother has approximately 4% African DNA and 6% Native American DNA:

This 10% of non-European DNA, for example, quickly dwindles to almost non-existent in the grandchild, as shown in the images and tables below.

Since I’ve actually tested two of the grandmother’s grandchildren, below are results for both.

Grandchild #1:

Grandchild #2:

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LegacyTree Genealogists Has a New Grandparent Mapping Tool

LegacyTree Genealogists is a genealogy research firm founded in 2004 and based in Salt Lake City but with professional researchers in many different places around the world. They do quite a bit of DNA work, which is how they got on my radar a few years ago.

Today, LegacyTree Genealogists released a new Inheritance Chart Tool for mapping a grandchild’s DNA to his or her four grandparents. The tool produces a chart showing exactly what segments of DNA came from which grandparent, along with a spreadsheet of those segments. There’s a blog post here: “Discover What You’re Made of with Grandparent Inheritance Charts.

One of the things I like best about this tool is the ease with which you can create a spreadsheet to upload and use the tool. At a minimum, you need three things:

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Quantifying Tree Availability for My AncestryDNA Matches

Last week, AncestryDNA announced that their database has reached 3 million people, and that they had sold 1.4 million kits on top of that in the last 3 months of 2016.  See “Ancestry Sets AncestryDNA Sales Record Over Holiday Period and Fourth Quarter” for more information.

This means that by summer or fall of 2017, the database is likely to reach 5 million people.

Many people have noted that many of these new test-takers will undoubtedly not have trees. That’s true, unfortunately, although it is a challenge rather than an absolute roadblock. It is an opportunity for experienced genealogists to engage new genealogists and encourage and help them. Indeed, many of them will never add a tree, and that will be very, very frustrating. But at least a small fraction of those will have a good reason for not doing so. The majority without trees will likely either not know how to do it, or may only be interested in ethnicity.

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Adoptee Testing: A Study

Today, Judy Russell at The Legal Genealogist published “DNA testing for adoptees: 2017,” an EXCELLENT primer for adoptees or foundlings looking to use DNA to find their biological family. If you’ve tested your DNA and spent time with your results, it is likely that you’ve encountered an adoptee looking for information. If you are an adoptee, Judy’s post is a MUST read, as it contains a NEW testing plan due to a new “pond to fish in,” a genealogy company offering autosomal DNA testing for the first time in 2016. Here’s the link, just be sure to come back after you’re done reading: “DNA testing for adoptees: 2017.”

The American Adoption Congress

Welcome back!

In April, I will be an invited keynote speaker at the 38th Annual American Adoption Congress International Conference in Atlanta, Georgia. In that keynote, I want to provide adoptees with information about how DNA can help them (for many this will undoubtedly be their first introduction to the power of DNA). However, I also wanted to share the experience of adoptees who test in the databases today. How often do they find biological family? What are their closest matches? And so much more.

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The Danger of Distant Matches

We know that small segments shared between two individuals can be problematic (see Small Matching Segments – Friend or Foe?), whether the two individuals are closely related or distantly related (or not related at all, as we’ll see). I call small segments (which I usually classify as 5 cM or less) as POISON because it is currently impossible to decipher between which are real segments and which are not.

In the following analysis, I use the wonderful new Match-O-Match tool at DNAGedcom to compare my and my parents’ match lists from AncestryDNA. The Match-O-Match tool is a powerful spreadsheet analysis tool developed by Don Worth. It is available to DNAGedcom subscribers as part of the DNAGedcom Client. For more, see page 10 of the PDF HERE. Thank you Don for this great new tool!

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Clustering Shared Matches

Given the lack of a chromosome browser, the Shared Matches tool at AncestryDNA is one of the most powerful tools available to genealogists. Once you have a list of genetic cousins at AncestryDNA, you can mine the Shared Matches with each of those cousins, looking for patterns of shared ancestry among the shared matches.

This works better if you have a well-researched tree and several tested relatives on multiple different sides/branches of the family.

PLEASE. I know I say this a thousand times in the post and the caveats at the end, but please use caution with this. I’m posting this because I found it useful, and I would like to get feedback on what others are doing in this area, particularly with regard to automation of this process. This is dangerous, so use caution!

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What is a Genetic Genealogist?

Is there such a thing as a “genetic genealogist” in genealogy today? Should there be such a thing?

In a previous post (“The DNA Era of Genealogy“) we talked about how DNA is a record type, similar to a census record, land record, vital record, or tax record. All of these record types provide evidence that – when combined with other types of evidence – support, weigh against, or reject a genealogical hypothesis.

However, DNA alone cannot prove anything; DNA evidence must be combined with other types of evidence in order to arrive at a solid genealogical conclusion. As a result, it is impossible to be a genetic genealogist and nothing else. To use DNA evidence properly (or at least to its fullest potential), one must also be a good genealogist.

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Assistance Needed!

As you know, I’ve been collecting submissions of known relationships and shared cMs for the Shared cM Project for about 1.5 years, and I have more than 10,000 submissions. (If you have submitted yet and would like to, the form is HERE).

I have a ton of data and recently provided an update (see “Update to the Shared cM Project“). However, there is still much to do. For example, I’d like to analyze the following:

  • Longest segment analysis
  • Known endogamy/pedigree collapse versus no known endogamy pedigree collapse
  • Company breakdowns (23andme v. AncestryDNA v. Family Tree DNA v. GEDmatch)
  • Others? (I’m open to suggestions!)

But I need help! I have time to oversee and assist with the analysis, but I just don’t have time to do it all myself. If you have statistics experience or are otherwise able to assist me with this project over the next month or two, please contact me at blainebettinger@gmail.com. Include your experience and your interest in the project. Thank you!

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The DNA Era of Genealogy

When does DNA prove a relationship? When is a triangulation group sufficiently large enough to prove descent from an ancestral couple? When is a shared DNA segment large enough to prove someone is your first (or second/third/fourth, etc.) cousin? At what point does the DNA prove that I am descended from Samuel Snell? When does the DNA prove that you’ve found your great-grandmother’s biological parents?

NEVER.

And this is, perhaps, one of the greatest misconceptions in the post-DNA era of genealogy.

What is Proof?

Genealogy is the study of lives and relationships. Accordingly, genealogists spend much of their time identifying, hypothesizing, supporting, and sometimes rejecting, relationships.

Unless you have direct knowledge of a relationship (and even sometimes when you do), you identify relationships using evidence that you’ve gathered from multiple different sources (including DNA, census, land, tax, vital, and many other types of records).

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Visual Phasing: An Example (Part 5 of 5)

Five-Part Series on Visual Phasing:

In “Visual Phasing: An Example (Part 1),” we identified and labeled all of the recombination points in the three siblings, Susan, Brooke, and Felix. Then, in Part 2 of the series, we used the identified and labeled recombination points to assign segments of DNA to the four grandparents (the blue grandparent and grey grandparent pair, and the purple grandparent and green grandparent pair). In Part 3 of the series, we used cousin matching to identify the grandparental source of the chromosomal segments. And finally, in Part 4 of the series, we characterized my paternal chromosome.

After Part 3, we had the following for Brooke, Susan, and Felix:

step4g

Now that we have this information, let’s see if we can use that to explore new matches with Brooke, Susan, and Felix.

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