How to Better Determine Relationships of DNA Matches

by Heather Murphy

When looking at DNA matches the various companies give you a general range of possible relations, close relative to first cousin, first cousin to great-nephew/niece, third to fifth cousins, etc.  While this is somewhat helpful, it is also somewhat vague.  Estimating the generational differences between matches and using tools from the Shared cM Project can significantly narrow the possible relationships of DNA matches.

A few weeks ago a "cousin" contacted me through one of the major DNA genealogical companies.  She was a genetic match with my grandmother and wanted to determine their connection.  After a few emails back and forth looking for a common ancestor about four or five generations back she told me her father, Tom (name has been changed), was adopted and she was actually working on finding his birth family.  My grandma's connection with her father was too far back to be of much help with the information she currently had, but I offered to help with her search.

The closest genetic matches for Tom was a first cousin and a great-nephew, per the estimated relationships the DNA testing company suggested. At my request, she sent me the information so I could review it.

The first thing to do with a genetic match is determine the generational difference between the two matches.  In this case, the possible first cousin and Tom were both in their 60s.  The cousin did not have a family tree posted, so I was unable to look at the actual generations moving backward.  While being approximately the same age puts them most likely in the same generation, it is not a certainty.  For instance, my mother was born the same year as her aunt.  However, for the time being my assumption is that first cousins is still a plausible relationship.

With the second match, the supposed great-nephew was in his 30s compared to Tom in his 60s.  In this case I did have access to his parents' information and they were in their 50s.  Most likely there is only one generation between Tom and this match, not the two generations that would be required for a great-nephew.  The age difference would suggest this match is related to Tom by only one generation, meaning one of this person's parents is a possible sibling to Tom.

Looking at the generational difference is only the first step.  Next, look at the number of centimorgans (cM) the matches have in common.  Tom and his cousin have 1,164 cM in common.  Take that information to The Shared cM Project, compiled by genetic genealogist Blaine Bettinger, accessed through the DNA Painter website. Input the amount of shared cM and you will receive a chart with the likelihood of certain relationships.  This is what it looked like for Tom and his possible cousin match:

dnapainter.com/tools/sharedcmv4

Since Tom and this match are most likely in the same generation, I look for probable relationships that reflect that.  In this instance, the only relationship that fits that description is first cousin.  Most likely Tom and this match share the same grandparents.

Now look at the second match's results:

dnapainter.com/tools/sharedcmv4

Looking for relationships one generation apart, the only likely option is that the match is Tom's half nephew, meaning one of this match's parents is Tom's half sibling.  By recognizing the generational differences and using this tool we were able to significantly narrow our search for a common relative.

At first, the assumed match was a great-nephew with the information from the testing company.  By looking at generational differences the assumed relationship changed to a nephew. Then, using the shared cM chart, the assumption changed to half-nephew.  This is an excellent example of how estimated relationships can change as we analyze the data regarding a genetic match rather than accepting the DNA company's estimation.

These examples are of matches that share a large number of cM.  In the examples above the amount of DNA shared resulted in a small list of possible relationships with greater than 90% probability.  Amounts of DNA less than 400 cM result in more possible relationships with a lesser degree of probability.  For instance, the chart may provide two groups of possible relationships with each group having a 40% probability.  This process will still help identify relationships with smaller amounts of shared DNA, but it won't necessarily narrow the options as tightly as larger amounts of shared DNA.

These tips are a good place to start when determining relationships between matches, but assumptions at this point are made from statistical probabilities and are not relationships of fact.  Further genealogical research and DNA testing are required to establish relationships with certainty.  With the number of possible common ancestors doubling each generation, using these strategies and tools can help focus your search for DNA matches more effectively by helping you focus on possible generations of common ancestors.

Beginner Class Introduction to the FamilySearch Catalog

Knowing how to use the FamilySearch Catalog will greatly enhance a beginner's knowledge of what is available on the FamilySearch.org website, in the Family History Library and the local Family History Centers.

Our April Beginners' Class covered a quick overview of the FamilySearch Catalog (formerly called the Family History Library Catalog), the different ways to search within the catalog, how to read a catalog entry and finally, how to download digitized books.

Here is the FamilySearch Catalog Handout which contains the links to the FamilySearch Wiki articles and other articles that go into depth on how to use the FamilySearch catalog.

The last entry on the handout, FamilySearch Catalog Exercise, is a set of questions to test your understanding of how to use the catalog.

Enjoy and thanks for attending the TCGS Beginners' Class.

Family History Discovery Day at the Richland LDS Church

by Connie Estep

This four hour event on March 24th was packed with all kinds of activities. They had a large exhibit area with a wide
variety of displays. TCGS member, Janet McKinnon, displayed family history games she made for her family. She had a set of blocks that could be rearranged to show 6 different photos, one at a time. She made them by cutting each photo into squares and gluing the photo squares to the block sides with just one square per photo to each block. They were all black and white photos with people and cars. The blocks fit on a small tray that showed the 6 pictures as a guide. Another was a set of homemade cards based on the game "Authors"; each card featured a picture of an ancestor with a list of facts about them. 

TCGS was represented at this event with a great display put up by Art Kelly. He included samples of various records spanning birth, military service, marriage, fraternal organizations and death. My favorite was the 1868 marriage certificate for his great-grandfather George William Kelly.

There was also a display of free genealogy handouts with info I found quite useful. One is titled “An Attempt to Answer Some Never-Ending Questions”; it includes help in sorting cousins. The “removed” cousins always puzzled me. No, they don’t divorce their families! It means two related people are in different generations. This includes a chart to make it easy to figure it out.

There was also a variety of classes. Although I helped Art at the TCGS display, I attended the story writing session where I definitely found new ideas!

The exciting part of the event for me was the “Coaches Corner”. I needed help finding information on my maternal grandfather and brought the little info I had to help. These grandparents were probably divorced at least by the time my mother was 6. She had given us a few details of her father (height 6’6”, shoe size 17). I had two records showing him: my mother’s birth certificate with his age and birth state and a Yakima City Directory entry giving a middle initial. Brian and David McShane were my coaches and great at negotiating on-line searches. They were able to locate a death record for him (we had never known his birth and death info before), a census record when he was 16, a WWI draft registration record giving his middle name (very helpful with a name like Robert Carson!), plus two employment records. This was a wealth of information compared to what I had before!

I am hoping with these clues to locate marriage and divorce records for this grandmother who was
incredibly unlucky in love! She moved with her family from West Virginia to Washington before she was four where the 1900 census found her. Married five times, her first marriage ended in 1916 when he died in a Montana coal mining accident. In 1918 she was in the Yakima City Directory living with husband #2 who she nursed until he died of tuberculosis. Her third marriage was the only marriage record I had found for her. It was in Los Angeles (Jan 1920) to an AWOL sailor who was already married. She found this out when the MP’s took him away soon after the wedding. Marriage #4 was to my grandfather; they were living in Sacramento in 1923 when my mother was born. This was her only divorce. The McShanes located the record for her final marriage: 1928 in Yakima, WA. She had contracted TB from husband #2 and was in and out of TB sanitariums during my mother’s childhood. She died when my mother was 10. She lived mostly in Yakima, WA after my mother was born, where her father and uncles lived. My mother gave me many of these details when I did an oral history with her.