Focusing on William A. W. Dempsey’s DNA Using Chromosomes Analysis and Segment Maps

I took a break from blogging to give myself time to work on a DNA problem. It was only supposed to be for a few weeks, a month tops. Except for my article on the flooding in our part of Europe, I haven’t posted any new content to my blog in two and a half months.

As many of my readers know, I’ve been doing genealogy for nearly three decades and blogging in my eighth year. Writing for my blog has taught me to be a better researcher and writer.

DNA is complicated

This may be one of the reasons people who have their DNA tested are more interested in their ethnicity than in looking into who they got their DNA from. Many are not into genealogy or have the time to spend hours analyzing match lists or creating quick bare-bones trees (also known as Q&D or quick-and-dirty trees) for matches. In writing this post, I hope to reach some of my many distant cousins who could help me with my search.

Understanding where the DNA comes from

I’ve been working with my brother’s autosomal DNA results for over five years, my own for nearly two years, and my mother’s for a year and a half. All three were done with AncestryDNA.

Maternal Matches

Mom’s test has helped sort the maternal matches but wasn’t really necessary. My brother and I have few matches who are descended from our maternal lines as our mother is Luxembourgish – with all known ancestors coming from Luxembourg or parts of France, Germany, and Belgium that were once part of a greater Luxembourg. Close cousins (4th cousins or closer) on AncestryDNA total 375 compared to the circa 3,000 that my brother and I have. Many of the 275 are descendants of Luxembourg emigrants who settled in America. Our mother is their link back to Luxembourg and helps anchor their DNA.

Paternal Matches

My brother’s and my autosomal DNA results have confirmed the paper trail we have for our known paternal ancestors for at least six generations. For some branches in the tree, we have confirmation for nine generations or more.

Color groups on AncestryDNA

To better understand where the DNA comes from, I worked out a color/group system on AncestryDNA that goes back to the 6th generation ancestors (my paternal 4th great-grandparents). This helps to sort new matches.

Screenshot courtesy of AncestryDNA.

As the parents of my 2nd great-grandfather, William A. W. DEMPSEY are unknown, the first group is for the 4th generation ancestors. This allowed me to split the HONAKER-WISEMAN matches into two sub-groups: HONEGGER-GOETZ (as HONAKER was previously written) and WISEMAN-DAVIS of the 7th generation. As can be seen by the numbers in parenthesis, these are large clusters of matches.

Abbreviations:
PGF – paternal grandfather (blue)
PGM – paternal grandmother (green)
MGF – maternal grandfather (pink)
MGM -maternal grandmother (yellow)

Using colors in the family tree

The colors I use on AncestryDNA for the groups match the colors used in genealogy software charts.

The pedigree chart courtesy of Ancestral Quest 16

Mapping the DNA segments with GDAT

The same color system has been used to map our known DNA segments using the Genealogical DNA Analysis Tool or GDAT.

Genealogical DNA Analysis Tool (GDAT)

Becky Mason Walker’s Genealogical DNA Analysis Tool (GDAT) is the repository I use to manage my DNA tests.

The database is stored locally on my computer and has no connection to the internet. I can import DNA matches from the different testing companies, do triangulation and in common with (ICW) comparisons, map the chromosomes of common ancestors, mark the most recent common ancestors (MRCA), add Ahnentafels (tress) of the matches, and do analysis work that helps with the family tree research. The tool provides easier-to-see patterns and clues to solve the genetic genealogy questions with all information in one place.

Segment Maps

I’ve mentioned the color groups, Shared Clustering, and GDAT in previous posts.

Look Who’s Finally Taken the Autosomal DNA Test

Unraveling the Mystery of George W. Dempsey, son of Seaton Y. Dempsey and Clementine Gowing (Part 3)

Mapping DNA segments is something I haven’t written about.

GDAT automatically maps DNA segments when the MRCA (parental/maternal side and group name) is identified. GDAT chooses the color for the segment but allows the user to change it using a color picker.

Autosomal DNA Segment Map courtesy of the Genealogical DNA Analysis Tool (GDAT). Group names on right for MRCAs for surnames B-J.
Autosomal DNA Segment Map courtesy of the Genealogical DNA Analysis Tool (GDAT). Group names on right for MRCAs for surnames K-W.

The DNA segment map shows the paternal (top) and maternal (bottom) sides of each chromosome. In the examples, the maternal side is mostly dark gray as we share WILDINGER-FOURNELLE (our grandparents/Mom’s parents) with our mother.

Although many of the maternal matches on AncestryDNA have been identified, very few segments can be added to the map as chromosome information is not available on Ancestry. Those seen are from FTDNA, MyHeritage, or GEDmatch.

This post is about my paternal matches and therefore only the top bar of each chromosome is of interest.

Comparing sibling DNA

The color groups on AncestryDNA as well as those in the family tree are used to map the DNA segments. For the example, below, the green, pink, and yellow groups have only two shades. I’ve kept these groups simple to show that siblings don’t share all of the same DNA. They share about 50% of the same DNA. Less color makes it easier to see the four groups of the grandparents.

My paternal grandfather’s paternal ancestry, the blue groups, include purple for first cousins who share all four color groups and red to highlight our DEMPSEY brick wall. A darker blue is used for second cousins and lighter blues for more distant cousins.

The maps show all segment matches that have been assigned a most recent common ancestor (MRCA).

Side by side comparison of siblings’ DNA segment maps for all generations.

On chromosome 1, my DNA segments are from my father’s paternal side: PGF (blue and red) and PGM (green). My brother received mostly DNA from our father’s maternal side: MGF (pink) and MGM (green). On chromosomes 5, 10, 17, and 19 we share more DNA from the same groups. Still, there are gaps – chromosomes segments that have not been identified (light gray, see chromosomes 6, 7, and 9). These are segments that could lead to several of the brick walls in our tree including the ancestry of William A. W. DEMPSEY.

The segment map in GDAT can be filtered by generation making it easy to see where segments are coming from.

Generation 2 (1st cousins)

Cathy’s segment map for 2 generations.

Purple segments are 1st cousins who share our paternal grandparents, Fred Rothwell DEMPSEY and Myrtle Hazel ROOP – the generation 2 ancestors. These include 1st cousins once removed (1C1R), matches from the younger generation. Seven of the 24 grandchildren of Fred and Myrtle are represented in this map. More would be ideal but I am happy to work with what I have.

Generation 3 (2nd cousins)

Cathy’s segment map for 3 generations.

The dark blue and pink segments cover the purple segments as they represent one generation further back.

Dark blue segments are 2nd cousins who share William Henderson DEMPSEY and Laura Belle INGRAM. Matches have been found for six of their eight children who had descendants.

Pink segments are 2nd cousins who share Walter Farmer ROOP and Rebecca Jane CLONCH. Three of their six children have tested descendants.

Generation 4 (3rd cousins)

Cathy’s segment map for 4 generations.

Red, more easily distinguishable from the rest of the blue groups, is for 3rd cousins who share MRCA William A. W. DEMPSEY (parents unknown) and Sarah Ann WOOD.

Green segments are the 3rd cousins who share Irvin Lewis INGRAM and Mary M. DEMPSEY (no known relationship to William A. W. DEMPSEY).

Pink segments are the 3rd cousins who share Gordon Washington ROOP and Milla Susan PETERS.

Yellow segments are the 3rd cousin matches back to Alexander CLONCH and Tabitha Ann COOLEY.

Chromosome Analysis

Adding another generation to the map further breaks down the larger segments shared with 1st and 2nd cousins and adds identification to some blank segments.

In the example for the 4th generation, the middle section of chromosome 1 now shows red where previously no color was seen. These are 3rd cousins who share the DEMPSEY-WOOD ancestors. This red section is not visible in the map showing all generations (see the first segment map earlier in this post) as it is a segment shared with matches who have more distant ancestors in common – ancestors of Sarah Ann WOOD, the wife of William A. W. DEMPSEY.

On this breakdown of the segments on Chr. 1, the red segment identified as generation 4 is also shared by matches who have HONAKER-GOETZ of generation 7 as MRCA. I received this DNA from Frederick HONAKER, father of Rachel HONAKER who married Elijah WOOD. This segment cannot be used to find more distant ancestors of my brick wall William A. W. DEMPSEY as the DNA is from his wife Sarah Ann WOOD, daughter of Rachel and Elijah.

Focusing on my father’s paternal grandfather’s side using the blue groups

What have I been doing these past two-plus months? I’ve been populating my DNA database with matches, trees, and notes. I’ve been focusing on my father’s paternal grandfather’s side using the blue groups. More specifically, I’ve been concentrating on the matches that, I hope, will lead to the parents of my 2nd great-grandfather William A. W. DEMPSEY (1820-1867) of Rockbridge County, Virginia, and Fayette County, West Virginia (then part of old Virginia).

The amount of DNA we receive from a particular ancestor decreases with each generation. There is a chance that very little or no DNA was inherited from a specific ancestor. An ancestor did not pass on the same DNA to each of his children. Those children, with their different combinations of their parent’s DNA, passed on different combinations to each of their children. The more descendants tested, the more DNA can be matched to the ancestor.

I need more RED! I need 3rd cousins who descend from William A. W. DEMPSEY to transfer their raw data from AncestryDNA to FTDNA, MyHeritage, or GEDmatch so that I can analyze the DNA using a chromosome browser.

By paying close attention to the MRCAs and the segments shared with cousins, I’ve been able to eliminate those who are related to me through Sarah Ann WOOD’s ancestors. Those are the lighter blue segments that overlap the red segments.

Sarah’s ancestors came from lines where many descendants have tested. The Wood, McGraw, Honaker, and Wiseman families were large and intermarried. All four lived in Monroe County, West Virginia (then still part of Virginia) at the time it was created from Greenbrier County in 1799.

While I have large clusters of matches for these four families, the mysterious clusters that are associated with William A. W. DEMPSEY are confusing. I hope that some of his descendants may share one or the other of the light gray segments (non-assigned DNA). This would help to identify the area that I need to research to open the door to this brick wall.

Light gray segments (non-assigned DNA)

  • The gaps on the chromosome map have plenty of matches but the common ancestors in my tree haven’t been identified.
  • Some of the matches have ancestors in common with each other but these aren’t names found in my tree.
  • Many matches have small or no trees to work with.
  • I need confirmed cousins on the segment to help figure out where the mystery ancestors may fit in my family tree.

I’ve identified 87 3rd cousin matches descended from William A. W. DEMPSEY through my great-grand aunts and great-grand uncles. Of these 87, only 17 have their tests on sites with a chromosome browser. Do any of the others share non-assigned DNA segments with my brother or me?

What further complicates my William A. W. DEMPSEY brick wall is the fact that his descendants have more than one connection to me due to marriages of grandchildren and great-grandchildren to spouses who descend from other common ancestors, i.e. Wood, McGraw, Honaker, Wiseman, Sims, Johnson, Kincaid, Ingram, and my other Dempsey line.

Why not try Y-DNA?

My connection to William A. W. DEMPSEY is through my father (Fred), his father (Fred), his father’s father (William H.), his father’s father’s father (William A.W.). This would make the males in our family good candidates for Y-DNA testing. I have a paternal uncle, three brothers, and nine male first cousins who are descendants of William A. W. DEMPSEY. My grandfather Fred Rothwell DEMPSEY had six brothers; his father William Henderson DEMPSEY had three brothers.

I don’t feel comfortable asking relatives to do DNA tests, either autosomal or Y-DNA. I don’t have the time or want to put the effort into a Y-DNA project. However, if a direct-male descendant of William A. W. DEMPSEY has done the Y-DNA test or is planning on taking it, I would be happy to work with them on the genealogy side. I have a feeling the Y-DNA surname is not going to be DEMPSEY. Maybe someone can prove me wrong!

Why I wrote this post

When I write my ancestors’ stories, weaving the facts into the story and checking off the sources used, I usually find unanswered questions. Writing actually helps me think through things. So this post was primarily for me, to see if I am on the right track with the system and procedure I use for analyzing the DNA. If I can explain it and it makes sense (to me), I hope it also makes sense to my readers.

I know this is beyond beginner DNA. This might give you an idea of how, maybe a bit further down the road, you can work with your results. You might also be more advanced and able to give me some feedback on how you would treat a similar brick wall. Comments are always appreciated.

Lastly, I’d like to thank the cousins who’ve given me guest access to their DNA. I hope this will help them see how very helpful their data has been to me.

© 2021, copyright Cathy Meder-Dempsey. All rights reserved.

Author: Cathy Meder-Dempsey

When I’m not doing genealogy and blogging, I spend time riding my racing bike with my husband through the wonderful Luxembourg countryside.

10 thoughts on “Focusing on William A. W. Dempsey’s DNA Using Chromosomes Analysis and Segment Maps”

  1. Wonderful post Cathy! DNA is a very necessary part of our research and the way you handle describing it makes it easier to understand. Thank you! Brian

    Liked by 1 person

  2. I am in awe of what you’ve done and still have no idea how to do it myself (or how you did it!). I have so many matches that match on both sides of my family that it’s impossible to do what you’ve done. For example, a new match came up on My Heritage—-she shares about 130 cM with me and a bit less with my brother, but only 100 cM with my mother. So I could parse out the part that came from my dad’s side by looking at the segments that are not shared with my mother. But then what? My father’s side is my better developed side, but there are so many twists in the tree—lines crossing when ancestors married cousins—that I’ve no idea how to identify which branch of the tree any match really came from. And it’s worse on my mother’s side since I can’t get beyond my great-great-grandparents’ names.

    And when I look at shared matches? Almost all my known matches (that is, those who I know from the paper trail) match matches from both sides of the family as well as thousands of unidentifiable matches.

    Bottom line: I envy those who can map things out this way!! Brava to you! And welcome back!

    Liked by 1 person

    1. Amy, I have a similar problem (but not to the extremes as yours) with my paternal lines that lived in the same area of West Virginia for over 200 years. Intermarriage is not in my direct lines but the descendants of my ancestors married back and forth. I have 6th cousins with 5 or more connections, sometimes twice through the same ancestral couple. The shared matches are all mixed up because of this. There is no way on Ancestry to know from which ancestor the DNA comes from. That’s one of the reason I want these cousins to share their raw DNA on sites with a chromosome browser.
      I often see this called endogamy but that is what you have, not what I have in West Virginia. So the segments these cousins share with me can be attributed to an ancestor as long as there are enough matches to work with.
      Thanks for the welcome back, Amy. I’ll be dropping in to catch up on your posts over the next few days.

      Liked by 1 person

      1. Well, I’ve tested or posted my results at Ancestry, MyHeritage, Family Tree DNA, 23andme, and GEDmatch. Doesn’t matter—none has been helpful in sorting out matches. 😦

        Like

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