The Importance of DNA to our Family History

Attendees at the Robbins Bicentennial Reunion in Indiana this summer had a great overview of the importance of DNA to Robbins family history by Greg Robbins of Florida.  I thought I’d provide a very brief recap to the discussion here along with my own thoughts.  Keep in mind: I’m no expert in this so others are welcome to share additional information or corrections in the comments.

It is that time of year when companies like Ancestry, 23AndMe, MyHeritage, and FamilyTreeDNA have sales on their DNA testing kits.  This usually happens around the family holiday season, as well as around Mother’s Day, Father’s Day, and DNA Day (April 23th this coming year).  If you are interested in testing your DNA this the time to get a kit at a greatly reduced price.

Why test your DNA?  The advertising from these companies is primarily focused on the ethnicity reports, that is discovering what region or country your ancestors came from.  This might be a disappointment to some as DNA is most accurate only to the continent level:  Europe, Asia, Africa, etc.  The testing companies constantly update their ethnicity results based on changes (updates to) their reference populations.  That is, they compare your DNA to others in specific areas (British Isles, Scandinavia, Southern Europe, etc.) to determine who you most match with.  The problem is that populations have not remained in one location over history.  The companies also change their groupings – Scandinavia gets divided into Sweden & Denmark as one category and Norway as another.  The results are interesting but I don’t find them particularly helpful for the type of genealogy I do.

The strength of DNA, as far as I am concerned, are with the matches identified between you and other testers.  Having a match with a distant cousin who claims descent from your probable ancestor helps cement that relationship and helps to prove out the paper trail that we were previously dependent on.

There are three kinds of DNA tests commonly available.  Autosomal (provided by Ancestry, 23AndMe, MyHeritage, and FamilyTreeDNA), and Y-Chromosome and Mitochondrial (only tested by FamilyTreeDNA.  The Y-Chromosome is passed down from father to son, so is useful with surname projects (i.e. Robbins surnames).  Mitochondrial is passed down from mother to children (regardless of gender) and can be useful similarly.  Autosomal is the DNA you inherit from both parents and is primarily that type that I have worked with.

As Greg mentioned in July there is a Robins/Robbins DNA Project based on FamilyTreeDNA.  This is most important for Robbins surnamed males – the idea being that they are descended, generation by generation, from other Robbins surnamed males and a compilation of the data will help sort out all the various s Robbins/Robins family lines.  I am not a Robbins surnamed male (my surname being Mittge) so a Y-Chromosome DNA test will not help me.  It is my understanding that the project can accept autosomal results but it’s much less refined, and thus less useful, than the Y-Chromosome testing, but I may try it one day.  I would encourage any Robbins surnamed males to test with FamilyTreeDNA and join the Robins/Robbins DNA Project.

I have worked almost exclusively with autosomal DNA results and primarily results through Ancestry.  I have also tested with 23AndMe and MyHeritage (as well as FamilyTreeDNA and a couple of others) but the data available through Ancestry is so large I’ve barely had time to move beyond that company.

You receive 50% of your DNA from your father and 50% from your mother, 25% from each grandparent, 12.5% from each great-grandparent, and so on.  Autosomal DNA is quite useful for a broad view of your genetic relatives but becomes less useful as you move back through the generations.  There is a point where you do not carry the DNA of particular ancestors because each child receives a random split of their parents DNA.  That being said, I have DNA matches with relatives who are fifth or sixth cousins, so obviously we each received some small amount of DNA from the same far distant ancestor.

Here is a chart from the International Society of Genetic Genealogy showing the likelihood of not sharing DNA with cousins as their relationship moves further away from you.  You will definitely match with a biological 1st cousin, while you have a nearly 70% chance of not matching with a 4th cousin (which still leaves a 30% chance that you will!).

The 50% autosomal DNA you receive from each parent can be somewhat different than the 50% that your sibling inherits.  That’s why it is important and very useful to test as many people as possible in your family.  Your sibling may inherit more of a particular ancestors’ DNA, while you may inherit more of another one.  You may match with a distant cousin while your sibling may not – it doesn’t mean they aren’t related, just that the bit of DNA from the common ancestor didn’t get passed to you or them. 

This chart shows four siblings with colored squares representing the DNA they have received from the parents, grandparents, and great-grandparents.  Each sibling is slightly different so testing each sibling is very useful for genealogy.

An example:  my brother shares much larger chunks of DNA with many of our Robbins cousins than I do.  He shares something like 147 cM (centimorgans, a unit of measurement of DNA) with one of our third cousins (another Robbins descendant), while I share 22 cM with the same person.  One of my brother’s matches, which I don’t share, is with a Robbins cousin who I believe comes down through the Chastain family – many, many generations away.  This is wonderful for sorting out and proving family lines.

I hope all of you consider DNA testing at some point.  It’s fun and extremely useful for family history research.  But –it’s up to you to test or not – you need to be comfortable with your decision – reasons not to test can include concerns about privacy, concerns about “surprises” you may not be comfortable with, not wanting to connect with strangers (albeit “biological” ones), and other reasons.  For me the decision to test was fairly easy, but we should all respect the choices of testers and non-testers alike.

And with that I would like to wish everyone a happy holiday season and a wonderful 2023!

August Miscellany: Reunion, Allied Families, and DNA

Robbins Bicentennial Reunion Update 

I have received a number of messages and emails about a possible 2022 Robbins Bicentennial Reunion in Decatur County, Indiana.  It’s wonderful to see the interest in this idea and I appreciate the offers to help.  While I don’t believe any of the people who contacted me are folks who actually live in Decatur County I’m going to continue to let the word spread and percolate and will come back to the project in the fall.  

Other Decatur County Surnames 

There are a lot of descendants of Jacob and Mary Robbins in Indiana, the United States, and around the world.  Focusing just on Decatur County descendants I wanted to list some of the “allied” families, that is, families who married into the Robbins family, no longer have the Robbins surname, and may or may not know of their Robbins ancestry.  There are likely Robbins descendants with these or other surnames in the county and some of you might recognize them.  

The list below is divided by the children of William, Absalom, Jacob, and James Robbins.  Besides those who moved out of state, a lot of family members moved next door to Bartholomew, Shelby, or Rush counties, or northwest to Indianapolis.  But this list, which is not complete, focuses solely on Decatur County. 

Children of William Robbins

Marmaduke:  House, Knarr, McCracken, Ralston, Scripture, Vanderbur

Elizabeth:  Owens

William:  Barnes, Evans, Kitchen, McCoy, Mendenhall, Mozingo, Pleak, Smiley, Smith, Stewart, Styers, Thornburg, Whipple, Wright 

Children of Absalom Robbins

Micajah:  Holcomb, Mozingo

Elizabeth:  Guthrie, Pavey

George:  Bower, Espy, Gannon, Giddings, Hood, Kutchback, Leisure, Meredith, Scripture, Shoemake, Stone, Voiles

Charity:  Allen, Jessup, Purvis, Skinner, Stout, Whipple 

Children of Jacob Robbins

William:  Harrison, Hartley, Miller, Spencer, Taylor 

Children of James Robbins

Matilda:  Terrell 

There are a lot of family members still in Greensburg and Decatur County but in compiling this list I was struck by how many families, especially since about 1940 or 1950, have left Decatur County.  Besides the neighboring counties mentioned above, and Indianapolis, many have moved on to Fayette, Boone, Scott, and other Indiana counties.  Much earlier in a time a very large group of descendants moved to Breckinridge County, Kentucky, while others moved on to Iowa, Missouri, Minnesota, Colorado, California, and the Pacific Northwest.  I hope to discuss some of these families in future blog posts.

Ancestry to Remove 6-8 cM Matches Soon 

As they do every few years, Ancestry is making changes to DNA results.  If you are an Ancestry DNA customer you may have noticed that they periodically update and change your ethnicity estimates – sometimes the results seem reasonable and sometimes they seem way off.  It’s a continual effort to make the results more accurate.  Each DNA testing company does this. 

This time Ancestry is planning on removing any match you have where the centimorgans (cM) are less than 8.  Or I should say the segment is less than 8.  Because you could have a match at 10 cM on two segments.  That would likely go away because both segments would probably be under the 8 cM threshold. 

Now, I’m no expert in using DNA results, though I have tried to teach myself as much as possible.  If you want a good overview of Ancestry’s proposed changes (now postponed to the end of August due to push back from the genealogy community), I’d highly recommend you read the DNAeXplained blog written by Robert Estes.  In particular, her first post, which describes ways to preserve these smaller matches:  DNAeXplained.

DNAeXplained screen shot

 Ancestry will not delete these smaller matches if you have (1) exchanged messages through Ancestry with that individual; (2) assigned the match to a “group”; or (3) added a comment on that match. 

My method is to pull up the matches (and I also do this with my siblings’ DNA results that I manage on Ancestry) and then filter for “Common Ancestors.”  The “common ancestor” listed is not necessarily accurate, because the information is based on members trees, and trees are not always accurate.  I’ve run cross a few of those lately.  But out of all your thousands and thousands of matches, I’d rather spend my time on those who have trees – whether public or private – and that’s why I do a “Common Ancestors” filter. 

Common Anc cM sort DNA

 You will probably still have a lot of matches in this group.  You can filter further.  You will notice that you can enter a custom cM range.  I started with 6 cM.  Note that on the right hand side of the entry for each match you can assign them to a group.  These are color coded.  A while back I created a “group” for each of my great-grandparents surnames.  In most cases I can identify each match to that level and assign them to a group.  By clicking on each match I can add a comment too, such as how they descend from our common ancestor.  I’ve been doing that with all of my matches, but starting at the top end, with those who I share a lot of DNA with. 

With these small matches, of which there are many, I may not have time right now to look at each individual match with a “Common Ancestor,” especially with an Ancestry deadline approaching and me planning on being away for a couple weeks of socially distanced camping and hiking.

2nd screen shot

So as Roberta Estes suggested, I created a group called “Holding Group.”  I can go straight down the list of these matches (without opening each one up) and put each one in my “Holding Group”, so Ancestry won’t discard them, and I can review them later at my leisure.  After working the 6 and 7 cM matches, I move up to 8 cM, then 9, and so on until I’m confident that the matches will survive Ancestry’s upcoming purge. 

What am I finding in these small – 6 and 7 cM – matches?  Between myself and my siblings I’m finding DNA matches with almost every branch of the Robbins family – not only through every child of William and Absalom Robbins of Decatur County, but also through their brother James Robbins of Jennings County and their sisters Martha and Mary who married Chastains and lived in Washington and Scott counties. And, surprising to me, even more distant cousins who descend from brothers or cousins of our most distantly documented ancestor, Jacob Robbins.  And I’m finding matches with descendants of the siblings of Bethiah Vickrey (who married William Robbins) and Mary Ogle (who married Absalom Robbins), as I descend from both of those couples.  I might have not found any of these if I had ignored these smaller matches. 

So, if you’ve tested with Ancestry, and have the time and interest, I’d highly recommend preserving those small cM matches.

National DNA Day

DNA Day, celebrated on April 25th each year, honors the discovery of the DNA double helix by James Watson and Frances H. C. Crick, and the beginning of DNA research as we know it.  But, more immediately for us, it’s an excuse for all the DNA testing companies to offer great price-saving deals.  If you were thinking of taking a DNA test, now is a great time to save some money.

The companies always reduce their fees during events such as this, as well as Mother’s Day, Father’s Day, during the summer, and around the Christmas holiday.  Check out the websites for Ancestry, 23andMe, FamilyTreeDNA, and MyHeritage for deals this week or even special one-day-only deals tomorrow.

One of the companies. FamilyTreeDNA, promotes various projects, as their site describes: “Projects create opportunities for people to work with others to explore their common genetic heritage. Family Tree DNA encourages customers’ participation in projects. Membership is free and voluntary.”

One of the projects they promote is the Robbins/Robins DNA project.  Their website is:  There are no restrictions on membership in this project and while the focus is on Y-DNA (passed from father to son), the results from mitochondrial (passed from mother to children) and autosomal (the DNA we receive from both of our parents) tests can also be included in the project’s results.  That’s good news for those of us who are not Robbins surnamed males – our Robbins descent comes down one of the many other lines of our family tree – who otherwise would not be able to use Y-DNA results to trace a direct male-Robbins ancestry.  I’m no expert in DNA and genealogy, despite attending lectures and seminars (such as the one last week my local genealogy society put on), and am always learning something new about it’s complex role in genealogy.

DNA projects and research are an important focus of today’s family history, but the science goes hand in hand with the paper trail that genealogists develop from their research.