RLP 220: Autosomal DNA Coverage – Part 1

Nicole (1s):
This is Research Like a Pro episode 220 Autosomal DNA coverage, part one. Welcome to Research Like a Pro a Genealogy Podcast about taking your research to the next level, hosted by Nicole Dyer and Diana Elder accredited genealogy professional. Diana and Nicole are the mother-daughter team at FamilyLocket.com and the authors of Research Like a Pro A Genealogist Guide. With Robin Wirthlin they also co-authored the companion volume, Research Like a Pro with DNA. Join Diana and Nicole as they discuss how to stay organized, make progress in their research and solve difficult cases. Let’s go.

Nicole (43s):
Hi everyone. Welcome to Research Like a Pro.

Diana (46s):
Hi, Nicole. How are you doing today?

Nicole (48s):
Pretty good. Tell me, how has your ancestral tree and DNA painter been going last week? You mentioned you were working on that. Are you doing the level up challenge still with that?

Diana (56s):
Yeah, I’m still working on that and as I was going through, and first of all, just adding if they are genetic matches each ancestor to me, I remember that I had this goal a while ago that I was going to start an air table base, where I could log all my paternal ancestors one for my paternal line one for my maternal line and keep track of the projects I’ve done on each one, because I’m getting to quite a few of these projects that we do in the study group, both the DNA and the regular study group. And so I have research logs, air table bases, reports, you know, lots of different iterations of projects. And so I started an air table base to do that.

Diana (1m 36s):
And I’m so excited. I really put some thought into the different fields. And so I’ll just explain what I did and you can gimme some feedback. So I have the ancestor and I’m actually using the ahnentafel numbers. And you can see those on the DNA painter ancestral tree. It actually numbers your fan chart for you. So that’s kind of cool. So this is my paternal line. So I have, my dad is the first one, Bobby Jean Schulz. And he’s number two because I’m number one. So he’s number two. And then I have the basic localities. I mean, obviously our ancestors have a lot of different localities. They lived in, but I’m, I’m putting birth and death and then maybe a couple other migration ones in there.

Diana (2m 22s):
And my thought is I could group by that, just to kind of see who is all in the same area for fun. Yeah. You know, I’m just thinking of ways I can use the grouping and sorting. I neglected to say right after the ancestor filled, then I have their dates. I have the basic birth and death dates. And then I did the research status that Yvonne white link did for her level up challenge. And so for my dad, he’s level three. I mean, I have his basic occupations residents and children, but there’s a lot of stuff I haven’t actually researched on him. You know, your own parents, sometimes you haven’t researched as much. And so then I have a column for notes where I say, I need to research world war II records for records, cuz he was in an organization in college school records and land.

Diana (3m 6s):
He had all sorts of land records. I’ve never looked at. And then I need to write a source site of biography. And then finally I have a link to his Google drive folder. And if I had a research log on him, I would have a link to that. If I’d done a project on him, I would have a linked field which goes to another table in my base, that’s called projects. So on that table I have got specifics about each project. So I have the person who’s in the project. I have the objective, the summary future research. And I have a column for if I’ve updated family search and my ancestry tree, the checkbox fields that are fun to check off.

Diana (3m 54s):
Then I also have another table in that base with the research status notes. So I’m just using what Yvette had created her, her levels. And so to remind myself, I can go look at that and see, okay, who is this? A 2, 3, 4, 5 or six one is names only. And so I will eventually have some ones, but I don’t have any of those yet.

Nicole (4m 16s):
Oh, you haven’t got that far yet.

Diana (4m 18s):
I haven’t gotten that far back. So I’m only on, I’ve done all the grandparents and great grandparents so far. So anyway, how does that sound?

Nicole (4m 29s):
That sounds like a great way to organize your own family’s research and just to be able to have a, a table at a glance that shows you people who need a little more research so that when you’re ready to write a biography of somebody, you can go ahead and get that done. And so is five of the highest level and that’s biography

Diana (4m 49s):
Number six is biography five is that you’ve met the genealogical proof standard. So, you know, I’ve done that with some of them, like I would say Benjamin Cox, I’ve, I’ve done a pretty good job with DNA and all the records. And I have a written conclusion basically of him, but I haven’t done really a biography. So I, I think someone that we’ve done a couple of iterations of a research report and feel like we really have them nailed down. We maybe have met the GPS on them, but haven’t done the historical context in a family history or biography. So that’s how I’m differentiating. And I have some notes again, I used Yvette’s blog post and hers was for Dutch ancestry or research.

Diana (5m 34s):
And so I’m kind of translating in that into the United States research and my experience with what you typically get first and then what you go after next. So anyway, it’s great in that field for research status, I’ll be able to sort by that to see, you know, who are all the ancestors that I have just this much on or just this much on, so air table’s really fun to, to put this into because it does have that sorting and grouping and filtering.

Nicole (6m 2s):
Yeah. And I like your idea to have links to your research reports and logs and things so that you can

Diana (6m 9s):
Right.

Nicole (6m 9s):
Remember what you have already done. Right.

Diana (6m 11s):
And so two of the ancestors that I have in here so far, William Houston Schultz and Dora algae, Royston, we’re part of my four generation project for accreditation. And so, you know, I have that in there as a project. And then on my project page, I have links to the log and the report and explanations about that. So I’m really excited to continue filling this out, getting in all the research I’ve done and then use that to keep going with working on my own family research. So I haven’t done a maternal one yet, but eventually I wanna do a maternal base as well. And I’ll share this with you because you could add all the research you’re doing on the same ancestors.

Nicole (6m 54s):
Oh yeah. Great. That’ll be perfect today. We’re gonna talk about coverage and we have talked a little bit about this in the past, but we’re gonna dive in a little bit deeper.

Diana (7m 5s):
Great. Let’s talk first of all, about DNA inheritance. So how much do we inherit from those distant ancestors?

Nicole (7m 14s):
Yeah, that’s a good thing to start with because when we’re using DNA test results to find evidence for a research subject’s parent, the typical method is to find DNA matches who are descendants of that hypothesized parent through different children. And you will only be able to find those matches if you actually inherited DNA from that ancestor. So the more distant the ancestor, the less likely it is that you inherited very much DNA from that person. You are expected to inherit about a, a quarter of your grandparents’ DNA, 25%. And then as you go back each generation, it reduces by half. So you are expected to inherit about one eighth of a great grandparents’ DNA or 12.5% and one 16th of a second.

Nicole (7m 60s):
Great grandparent’s DNA, about 6.2, 5%, one 32nd of a third great grandparent’s DNA or 3.1, two, 5% and so forth. So one 64th of a fourth, great grandparent and 1, 1 28 of a fifth great grandparent.

Diana (8m 16s):
Wow. That is such a small amount of DNA coming from those, even with the third, starting with the third, fourth and fifth, that’s just a tiny bit of our entire DNA that we get from each of those, those great grandparents. So, you know, it’s really important to understand that and isn’t it so fun when you actually look at different grandchildren and see how much they inherited from different grandparents? How, you know, it’s not that exact 25%, right?

Nicole (8m 46s):
Right. Yeah. Those are just estimates. So due to recombination, the amount you actually inherited from each grandparent and each ancestor is not exact. And I, I actually was able to compare my DNA results with my grandparents and see how much DNA we actually share because three of them have tested. And so I found that I inherited 22% of my paternal grandfather’s DNA and 28% from my paternal grandmother. So it was not an even 25% age. So if I didn’t know that and I wanted to go find a more distant ancestor on my paternal grandfather’s side. And I happened to choose one of his lines that I didn’t get that much DNA from then I wouldn’t probably be able to find any matches relevant to my research project.

Nicole (9m 35s):
If it’s distant enough, you know, three or more generations back from my grandfather, because I’m already starting only at 22% of his genome.

Diana (9m 44s):
That’s a really interesting thing to think about. And you are lucky because you actually have, you know, DNA from both grandparents that you can look at that. But for many of us, we don’t even have our parents tested. And so we have no idea how much we got from each grandparents. So it’s just important to realize that we’re going to have different amounts. So something to think about is that we’re not even going to have all of our ancestors represented in our genome. So we have a genetic family tree, but then we have clear out if we can imagine a fan chart clear out on those outer edges, we’re going to have ancestors that we just lost their DNA. It just didn’t come all the way down to us.

Diana (10m 25s):
It got lost in one of those generations. So we have our genealogical family tree and then we have our genetic family tree. And so this is why it’s really important that we work on getting appropriate DNA coverage from our autosomal matches. So autosomal, those are the matches that we get on ancestry and we get on all the different companies, not why DNA, not mitochondrial DNA, just that DNA that we share with all of our cousins. So Paul Woodbury has done a lot of teaching on coverage and we so appreciate everything. He teaches us about this. And he says, coverage refers to the amount of a research subject’s DNA that is represented in a DNA database through their combined tested descendants,

Nicole (11m 13s):
Right? That definition is helpful because, you know, we can think about all the people who descended from our ancestor that we’re working on, who’ve tested. And the fact that they’ve tested is great, but it’s even better if we have access to those results to help find relevant matches. So when we’re talking about coverage, we’re talking about usually us as a researcher, having access to those DNA tests of those descendants so that we can analyze their matches and find relevant matches that help give us evidence of our hypothesized parent of the ancestor. In question to learn more about coverage. Paul has written and lectured about the importance of testing multiple descendants of a research subject to achieve better coverage.

Nicole (11m 57s):
And so I recommend watching his webinar cram Derem targeted autosomal DNA testing to isolate pertinent genetic cousins, and that’s available on legacy family tree webinars. And he talks about the concept that different descendants of your research subject help illuminate different part of that research subject’s genetic profile. And he uses the example of a portrait. And I love this example of a portrait of our ancestors. It’s kind of dark. And when one of their descendants takes a DNA test, it’s like illuminating one part of that ancestors face with, with the flashlight. And so like a small part of it is now illuminated.

Nicole (12m 40s):
And then when another test taker takes a DNA test, who’s descended from that ancestor through a different way. The ancestors face is now illuminated with at another part. And sometimes those circles of illumination overlap a little bit and sometimes they’re different and highlight a new part of their portrait. And this is just a really helpful way of thinking about coverage because the more of our cousins who descend from that ancestor test, the more that their genetic profile is illuminated to us. And we can understand who their parents were and we can use DNA matches to help us with that. So if you haven’t seen that webinar, I totally recommend it.

Diana (13m 20s):
I love that visual of an ancestors’ face and illuminating a little bit more of that portrait. When you add more DNA, it’s just such a good visual. Well, let me just give another example from my own research. And I’ve talked a lot about my Rachel Cox and Benjamin Cox, but I, one of the key things that I learned in genetic genealogy was to get more test takers, to get more coverage because I was mapping out all of my connections to Benjamin Cox through Rachel Cox. And I attracted, you know, these different descendants of his children. He had a lot of children, but my matches were relatively small.

Diana (14m 2s):
They were from as small as six Centor up to 18 Centor was my largest. And most of them were about 10 or under. So, you know, even though I had a lot of matches, those just were such small numbers. And you would suggested that I have some other descendants share their DNA with me because they would’ve inherited a different piece of the genome from Benjamin Cox. And I could look at how they matched other people and get more coverage of his DNA. And so I had four different descendants of Benjamin Cox share their DNA results with me. And I charted out how much they shared with the other descendants.

Diana (14m 46s):
And, you know, I have a really large chart of this, but I was able to find three people that were, were a generation closer than me and they shared higher amounts. So now I’m up in the twenties and the thirties with amount of DNA shared. So just increasing the coverage and getting this really nice cluster of people that are all related, helped provide so much more evidence than just my poultry results because Benjamin Cox is back aways for me, he is my fourth great grandfather. So great. I would have maybe inherited 1.5, six, two, 6% or maybe not.

Diana (15m 30s):
I might have inherited less than that. So

Nicole (15m 32s):
Yeah. More or less possibly who knows.

Diana (15m 35s):
Right.

Nicole (15m 36s):
Okay. So a couple follow up questions. So your coverage that you were increasing was your coverage of Rachel Cox, right? Because each of the people that you asked to share their results with you were descendants of Rachel, right?

Diana (15m 49s):
Only two of them were. Then I had two other people that were descendants of different children. So I had a descendant of Sarah Cox and a child of William Thomas Cox. So I had three of the children of Benjamin Cox represented. So I was able to increase the coverage from just one of his children to three of his children.

Nicole (16m 10s):
Oh, so you increased Benjamin Cox coverage to show that all those children were related right. To Rachel Cox, cuz you were trying to prove Rachel was a daughter of Benjamin. Right?

Diana (16m 20s):
Right. And then I had two additional descendants of Rachel just like me. I looked at their results too. And so we had three of Rachel’s descendants, one of Sarah’s and one of William’s descendants. So three of the children represented looking at their DNA results that I had DNA matches to all of the other children through the five of us.

Nicole (16m 47s):
Fantastic. So the takeaway from this example is that sometimes you might find that you have a lot of matches and you may wonder are these matches good evidence or not because they seem really small. And that was what happened with this. And that’s why we decided to expand the test takers, to get better evidence, to increase the quality of that evidence, to see if more than one descendant of Rachel Cox was matching with more than one descendant of Benjamin Cox. And so by increasing the coverage, the quality of the evidence went up. Sometimes we don’t even have any evidence at all. So that’s what I’m gonna talk about in our next example.

Nicole (17m 28s):
And in the next episode two, we’ll talk about that. So sometimes we just need to increase our coverage in order to find any matches to help us. Right. So that’s good that you already had some, so let’s do our next example. So in episode 204, we had talked about recruiting test acres for an autosomal DNA project. And so I did talk a little bit about the Arnold project, where I was working to discover the parents of Daniel Arnold. And when I first started working on the project, I had the test results of just one person, a second great grandchild of Daniel. And so at that point, the coverage of Daniel was only about 6.2, 5%. You know, that’s still just an estimate, but that’s kind of how we calculate coverage.

Nicole (18m 10s):
We calculate it using those estimates of how much a second great grandchild might inherit in the blog post that we’re gonna link in the show notes that goes along with this episode, you can see a chart where I have included the coverage that we started off with for the Arnold family. And so in the descendancy diagram, the test taker is a hundred percent covered of his own genome. And then his test results cover 50% of his father’s genome and 25% of his grandfather’s genome, 12.5% of his great-grandfather Aus George Arnold’s genome, who was the son of Daniel Arnold. And then 6.2, 5% of his parents, genome Daniel, Arnold, and Lydia Willie.

Nicole (18m 55s):
And so one thing to think about is that that coverage for Daniel Arnold is actually for him and his wife because we’re focusing on descendants of both of them. And so we actually don’t know sometimes if that 6.25% that the test taker maybe inherited something around that amount came from the Daniel Arnold’s side or from the Lydia Willie side. So that’s another thing to consider too. So if we’re trying to find Daniel Arnold’s parents, then some of that DNA may not have come from them, may have come from Lydia’s side. And that’s one thing I found in, in my brushy, our research, which will talk about in our next episode. So you can go ahead and look at that chart in the blog post, the blog post is called find more ancestors with autosomal DNA by increasing coverage.

Nicole (19m 39s):
And there’s a bunch of examples in there of how to make your chart so you can get some ideas. But what I ended up doing with this chart was to use like a dark orange color for people who are a hundred percent covered and then kind of fade the orange up to like a light orange for people who just have 6% coverage so that you can see that when somebody gets more coverage, they get darker.

Diana (20m 0s):
Yeah. I love your chart and the way you did the coloring and as always drawing out a chart helps you visualize what you’ve got. Otherwise, it’s really hard to wrap your mind around this concept, but looking at it makes it really clear. I love that. That you’ve figured out a good way to do a nice diagram for us.

Nicole (20m 22s):
Yeah. Yeah. So as you can see by this first diagram and the blog post, it’s easy to estimate the coverage when you just have one test taker, because each generation that you go up, you just divide the coverage by two, so a hundred percent, 50% and so forth. But what happens when you add another test taker? At that point, the calculation to estimate coverage becomes a little trickier because each descendant inherited some of the same DNA and some different DNA from the research subject. So Paul Woodbury uses a Venn diagram to illustrate this concept. And the part that’s in the center of the two overlapping circles is the amount of DNA that was probably inherited in common between the two test takers.

Nicole (21m 3s):
And then, you know, the other parts are what those two test takers inherited. That’s different from each other. And that’s the part that increases the coverage. So you have to kind of subtract out that center part where they overlap, because otherwise you would get way more coverage than is actually probably true, especially for like siblings. If you think about siblings, they inherit some DNA, that’s the same. And some DNA that’s different, but if they inherited completely different DNA from each parent, it’s extremely unlikely that that would be happening because you know, all siblings have some things in common and, and some things that are different. Right,

Diana (21m 39s):
Right. And that makes sense. I think it helps us understand that when you think in terms of siblings, how you had some in common and some not in common. So just to get this straight, we can think of a Venn diagram where we have a circle with one person’s D inherited DNA in a circle with another person’s inherited DNA. And then there’s a section in the middle that is the same DNA that we subtract out to figure out the coverage.

Nicole (22m 5s):
Right. Yeah. So then you’re loved with an estimate of an amount that those two test takers got uniquely from the parent. So for example, with the Arnold’s we have Keith’s son who took a DNA test and then also his uncle Albert’s son who was in the database. So I asked if I could have access to Albert’s son’s matches because he was one generation closer. And so that was kind of the first way that I increased the coverage of Daniel Arnold to illustrate how Keith and his brother inherited some shared DNA from their father. I made an example, Venn diagram that you can look at on the blog post. And the middle section shows that they inherited about 25% of the same DNA from their father, Keith and his brother have some unique DNA from their father Albert and some DNA in common.

Nicole (22m 54s):
So that helps us see that we can’t just add up the percentage of coverage of each son. When we calculate their father’s coverage, we have to estimate how much they share in common and subtract that from the total coverage to figure that out, we could just take all the DNA that one son inherited from his father, and then add on only the unique DNA that the other son inherited from his father without adding in that middle section that they share with each other. So it’s okay if you don’t really follow everything here, don’t worry. Paul Woodbury has given us the calculation for how to do this. And so we can just use his calculation and in the formula for this calculation, the lowercase letter, a stands for half the coverage of child uppercase a and B is half the coverage of child uppercase B.

Nicole (23m 43s):
And so coverage equals a plus B minus a times B. And that a times B is the amount that the two siblings would share in common with each other. So to calculate Albert’s coverage, we would take Albert’s son’s coverage 100% or one. So instead of using a hundred percent, we use one and then we use decimal points for the 50%. So 0.5 for 50 and so forth. So we take one, we divide it by two, which is 0.5. And we plug that to the a and the coverage formula. So we put in 0.5 for the first child, a and then we take Keith’s coverage, which is 50% because his son tested.

Nicole (24m 25s):
And we divide that by two, which is 0.2, five. And then we plug that in for the B in the coverage calculation. So we have coverage equals 0.5 plus 0.25, and then minus a times B. So we multiply 0.5 by 0.25. And that’s the amount they probably share in common from their father, which is then subtracted out. So five plus 0.25 minus 1, 2 5. And that gives us 0.6, two, five. So then we have 62.5% coverage for Albert. Albert is the son of AMO George Arnold. Who’s the son of Daniel Arnold.

Nicole (25m 6s):
So that helped us increase our coverage of Daniel Arnold to 15.6, two 5%. That is more than double the coverage we had before by adding in the original test uncle.

Diana (25m 16s):
Wow. That’s amazing. And I’m really glad that Paul has a formula for us, right?

Nicole (25m 23s):
Yeah. Writing this blog post really had to like study the way it worked and think about it. So hopefully this is helpful to people.

Diana (25m 32s):
Yeah. And I think as long as you have the basic idea, and then you just know the formula, you can do it. Right.

Nicole (25m 40s):
So that was what we used for the first phase of this project. You know, we searched for DNA matches to the original test taker’s uncle, and we found some matches that were helpful in identifying possible siblings to Daniel Arnold. So that was really exciting. Then we decided to go forward with another phase of this project. And with that phase, we just focused on documentary research. And then the third phase, we decided to go back to the DNA and increase our coverage of Daniel Arnold and get more test seekers in order to see if we could extend our hypothesis back a few generations to see if we have the right people. Because the woman who the mother of Daniel Arnold, we thought was her tree went back a few generations.

Nicole (26m 25s):
So we thought let’s test out if this is the mother of Daniel Arnold, by seeing if there’s matches to her side of the family. But since it was further back, we knew we would need to get more test takers. So that was the first step of that phase was increasing the coverage. So we found three additional test takers, but all of them were through Amos, George Arnold, one of Daniel’s sons. And we really wanted to find more matches from some of the other children, but it didn’t end up happening. And that was okay because we still got 31% coverage of Daniel Arnold and Lydia Willie through increasing the coverage of Amos. And so we were able to be successful in finding DNA matches that confirmed the mother of Daniel Arnold.

Nicole (27m 7s):
So even if you can only get, you know, like 30% of somebody born in the early 18 hundreds, that’s a pretty good amount,

Diana (27m 14s):
I would say. So, especially when we’re considering what we start with from someone like one individual person, doesn’t not share that much DNA with that ancestor that far back. So if you can get to 30%, I think that’s pretty great.

Nicole (27m 29s):
Yeah. And what that does is just make it possible to find more matches to descendants of Daniel Arnold’s, hypothesized cousins, you know, his siblings, children, his aunt and uncles descendants and his great aunt and uncles descendants. So it just makes it possible to catch the matches with them that we otherwise wouldn’t see, because we, we have such a small fraction of his portrait illuminated in the database,

Diana (27m 52s):
Right? So kind of to wrap up this episode here is our final thought, the more coverage you have, the more relevant matches you will find just what you were saying, Nicole. And this really is the exciting part of increasing coverage because it helps us discover matches who will either help us form or test the hypothesis for the parents of our research subject. So, you know, sometimes people get stuck. They don’t know what else they can do with their DNA. And this happened with someone I worked with last week where they just didn’t know what else to do. And this whole idea of adding in more DNA was just so illuminating for them.

Diana (28m 31s):
So hopefully, you know, everyone listening will get the basic idea that we want to just get more coverage. Think of that ancestors portrait and more descendants coming down from that ancestor from different children will shed more light on that portrait.

Nicole (28m 48s):
Yeah. I was gonna say the way that I learned what needs to happen in order to use DNA evidence was by studying people who had successfully proven a case of parentage. What I studied were articles in the national genealogical society quarterly. And what I found was that they were all using multiple descendants of their research, subject, their ancestor to help them test hypothesized parent. And so they didn’t just have their own results. They had like their results, their cousin, their aunt. So they were usually at least three people who they had tested.

Nicole (29m 28s):
And so that was kind of eye-opening that, you know, if we’re going to prove a case, that’s further back in time, we need to get better coverage of our ancestor to have quality evidence. Like we were just reiterating. It’s not just the quality of evidence that coverage helps you with it’s the quantity. And so if you’re not finding any relevant matches, it could be that you just didn’t inherit a lot of DNA or any DNA from that distant ancestor that you’re working on and finding another test taker who maybe did inherit a lot of DNA from that ancestor can really help you find the parent of the ancestor that you’re looking for. So in our next episode about coverage, I’ll talk about just that and how the original test acre I was using to find Bari bihar’s mother just didn’t inherit a lot of DNA from her.

Nicole (30m 10s):
And so I expanded and increased the coverage and that helped solve the case of who her mother was. So I’m excited to talk about that and share a little bit more about coverage.

Diana (30m 21s):
Well, I’m looking forward to talking more about Barba art and how you are figuring out her. It’s so great because you know, a woman born in the early 18 hundreds, figuring out her parents, that is one of the hardest things to do. So it’s gonna be fun to talk about that one next. So we hope everybody has a great week and we’ll talk to you next time. Bye-bye everyone. Bye

Nicole (30m 42s):
Bye. Thank you for listening. We hope that something you heard today will help you make progress in your research. If you want to learn more, purchase our books, Research Like a Pro and Research Like a Pro with DNA on Amazon.com and other booksellers. You can also register for our online courses or study groups of the same names. Learn more at FamilyLocket.com/services. To share your progress and ask questions, join our private Facebook group by sending us your book receipt or joining our courses to get updates in your email inbox each Monday, subscribe to our newsletter at FamilyLocket.com/newsletter. Please subscribe, rate and review our podcast. We read each review and are so thankful for them. We hope you’ll start now to Research Like a Pro.