Genealogy and DNA – get comfortable first

Disclaimer: I am not a DNA expert. This blog post reflects how DNA is used in genealogy as I understand it at the time of this posting.  I am still learning and the technology is still evolving.

In my post for John Rhoads, I mentioned the use of DNA for genealogical research.  Initially, I used the AncestryDNA product to complete an autosomal test for one of our relatives.  This type of DNA test provides a broad picture of a donor’s DNA make-up using autosomal chromosomes, that is DNA inherited from both male and female ancestors.  I selected a sibling of the autosomal donor to complete a Y-chromosome DNA (Y-DNA) test, which is gender specific.  The Y-DNA is specific to male DNA testing so will relate specifically to our Rhoades lineage, omitting any other family lines.

Now, to be clear – we do not inherit exact percentages from our parents.  This means, that while our grandparents may have come from France, Scandinavia, Ireland, or say…somewhere in Asia, respectively, it does not mean we inherited exactly 25% of each of their DNA.  We can, and do, inherit more DNA from certain ancestors than others.  Also, siblings can inherit different percentages of DNA from the same set of parents and grandparents.  I won’t even try to touch on recessive genes.  Consider also, our ancestors did not have JUST Irish DNA, or JUST French DNA, even if they had been “fresh off the boat” in America.  People traveled, even before America was colonized – people traveled.  Our French and Irish ancestors had ancestors of their own from other places. Inter-racial and inter-cultural marriages are not a new phenomenon in the United States.  They have been occurring for as long as humans have been migrating.  Our DNA is not as exacting as we might think.

Here’s my plug.  Ancestry commercials make DNA testing appear glamorous with instant answers to your lineage.  It’s not as easy as they would like us all to believe.  If we all knew how complex it is, Ancestry wouldn’t sell DNA kits.  Leave it at that.

Autosomal DNA

What did this test reveal in the case of our autosomal donor?  I chose a relative who is not biologically related to my mother.  Why?  Because my mother is from Asia, her parents are Asian, her grandparents are, you guessed it… Asian.  You get the picture.  Well, why not me with my Rhoades DNA?  I am my mother’s daughter; therefore I am very much Asian in my genes.  I wanted an undiluted non-Asian sample related to my Rhoades ancestors so that I could focus on a specific genealogical line.  Also, I wanted to look into potential Native American suspicions (see the Native American assessment further in this post.)

I converted the raw data from AncestryDNA to Family Tree DNA (FTDNA) to compare the results of two independent DNA analysis.  You can see the comparison of the two results later in this posting – interesting.

All DNA test types can give you a picture of what region of the world your DNA originates from, and all can tell you what level of relation you are to other test samples.  Each test has varying levels of accuracy. Autosomal DNA is the least accurate as it becomes less accurate with each generation.  The median accuracy occurs in identifying 4th cousins.  So, any match you receive beyond 4th cousin relationship is less than 50% accurate.  This means:

  1. Other people from the same ancestors must test with the same lab as us
  2. For autosomal tests, of those tested whom we match, we want to focus on any hits that identify 4th cousins or closer
  3. All participants must publish their traditional genealogy research to determine more specifically how and where matches are related

Autosomal tests are not specific to one family line.  This means it looks for any matches to your DNA and those matches can be from anywhere in your family tree, making point 3 above instrumental for success.

AncestryDNA’s visual depiction of a 4th cousin relationship.  Basically, it is the great-great-grandchild of your great-great-grandparent’s sibling.  DNA can only provide a 50% accuracy rate at this level.

The Ancestry DNA results have produced genetic matches to:

  • my paternal grandmother’s sister (yes, she tested)
  • two 2nd cousins
  • eleven 3rd cousins
  • >twenty 4th cousins

The analysis is ongoing to the matches above. Most Ancestry DNA participants have not published their genealogical research so I have no idea how they relate to us.  However, I have identified the following:

  • at least three are Alig relations
  • two have Rhoades connections – but their research only goes back as far as ours (they are related through John Rhoades’ other children)
  • two have a Weigle/Wiggle surname in their tree
  • one distantly (beyond 4th cousin) matched our Gage ancestry
  • one distantly (beyond 4th cousin) matched our Rhoades lineage to Westmoreland county also – we’re research pals now.

The genetic matches provided on FTDNA are not as good – not because of the test results (we have plenty of matches, actually), it’s because fewer people publish their tree on FTDNA. Even I haven’t finished publishing ours on FTDNA 😔  People on FTDNA have more interest in the human genome project than genealogy, though I have met one more Westmoreland, PA connection through FTDNA.  She can trace her Rhoades/Roth’s to Bucks County.  Her match was through the Y-DNA connection…read on.

Gender Specific DNA

To limit DNA testing to a specific family line, you have to use the Y-DNA test (links sons to fathers, to grand-fathers, etc.) and Mitochondrial DNA test (mtDNA; links child of either gender to mothers, to grandmothers, etc.  Male children inherite mtDNA, but do not pass their mother’s mtDNA.  Only mothers can pass mtDNA on to children).

Our next relative was chosen for a Y-DNA test.  I was trying to pinpoint the John Rhoads brick wall to answer: who was his father or grandfather?  I have already expressed my frustration in part 2 of the blog posting for John Rhoads.  Y-DNA testing is pretty darn accurate (notice I did not say 100%) and can confirm genetic matches for up to fifteen generations back – better than autosomal testing.

Our Y-DNA donor’s origins map with insert for member DNA matches on FTDNA.  Notice who’s first on the match list!

FTDNA writes: Y-DNA tests trace both recent and distant generations. The number of generations traced by a Y-DNA test depends on the type of test taken, short tandem repeat (STR) or single nucleotide polymorphism (SNP).

  • STR tests are able to trace a male lineage within genealogical times and into historic times. FTNDA has used the STR tests to provide a report on genealogical/DNA matches to other FTDNA members as they relate to our Y-DNA donor.  Matches include those who only completed an autosomal tests.
Our Y-DNA donor’s Ancestral Origins results from FTDNA. Twelve markers show we are most recently related to English, French, German, and Irish regions. Further along in history, the 37 markers show we are of Germanic origins. Even further back in history, we are still of Germanic origins.  There were not enough 111 marker samples to compare to (the furthest back the tests will go).  There is no specific timeline provided for each step in the markers.
  • SNP tests are able to trace both ancient anthropological migrations and more recent prehistoric movements. A Y-DNA SNP test also identifies the haplogroup, which represents your deep ancestral origins (tens of thousands of years ago). Our Rhoades’ DNA is confirmed as R1b-Z156 haplogroup which is heavily associated with northern mainland Europe, British Isles, and Scandinavia.  If you think I am speaking Greek try reading this.

OK, so, what did the Y-DNA test do for us? It matches a man’s SNP results with another man’s SNP results to tell you how similar they are.  The more similar, the most likely you have a male ancestor in common – then you become research companions.  The more men you have tested (preferably from independent family lines) who you suspect to have a likely common ancestor, the more likely you are to confirm a male progenitor.  CAVEAT:  You still have to be able to find the paper-trail proving you both come from the same male progenitor.  Unless you dig up your candidate to test DNA from their bones – could you imagine the chaos if Genealogist all over the country descended on Eastern states and started digging in the oldest cemeteries?

I entered our relative’s Y-DNA results into the Roth DNA project on FTDNA and found one very close match to a Roth family in Bucks County, PA, the same family that moved to Westmoreland County, PA (see John Rhoads). This is the woman I mentioned at the end of the autosomal section of this post.  Her uncle and our Y-DNA relative tested closest in SNPs of all the Roth project members with her haplogroup being R1b-M269, this subclade is “upstream” of our R1b-Z156.  I think that means it’s an older haplogroup than ours. I know – Greek.

Sample of the spreadsheet from the Roth surname project on FTDNA. This just shows the R1b Haplogroup deep ancestral matches.  This is a very large spreadsheet and makes your head spin.  Our Y-DNA donor’s results are in the red box.  You’ll just have to take my word for it, if you were able to scroll to the right in the spreadsheet – you would see more or less matches to the other lines.  All the numbers represent the different SNPs in a DNA sample.  The colors in the SNP fields represent a deviation in SNP results (+ or -) from the average in the R1b Haplogroup.

I was a little disappointed in how few we matched in the Roth surname project, but it did three distinct things for my research:

  1. It confirmed my hypothesis that our Rhoades’ are related to Roth’s who were from Germany (or Prussia for the time we are looking at), not England.  
  2. It provided more evidence that the Westmoreland, PA Rhoades/Roth family is likely related, and furthermore, can be traced to Bucks County, PA as far back as the early 18th century.
  3. It taught me something new; the Roth surname did not originate only in Britain and Prussia/Germany.  The surnames in this project are from all over Europe and Asia minor (Turkey region), each with their own independent morphing from the original surname to Roth, and then on to Rhoades in many cases.

In order to learn more about a maternal line, we have to find a living descendent as follows:

At this stage continued DNA research for the purpose of genealogy has to be calculated.  In other words, we can’t expect results by waiting around for new hits on AncestryDNA or FTDNA.  I will have to actively seek other descendants with good paper connections to a hypothesized ancestor and convince them to complete a DNA test to see if they match.  By doing this, we can show a genetic relation to their known ancestry thereby forming evidence of our own genealogical connection – break a brick wall.  Like finding a needle in a haystack restricted by limited funding.

Ethnicity Results

FTDNA for both of our DNA donors came back with similar percentages.  We were intrigued by the percent of Scandinavian markers in the results.  So here is what FTDNA had to say about how we came by our Scandinavian DNA:

Chieftain tribes ruled ancient Scandinavia, and the Viking Age was born around 800 CE in the bay between the Gotta River in Sweden and Cape Lindesnes of Norway. Between 800 and 900 CE, Viking populations had taken control of trade from the Dnieper River to the Baltic Sea and Constantinople, connecting them to populations as far away as the Middle East, Western Russia, and Siberia to the east. During the Viking Age (800 – 1050 CE), Vikings spread throughout the Old World in raiding and settlement parties. Vikings traveling west spread as far as North America and conquered areas between (such as Ireland, Scotland, England, France, Iceland, and Greenland). Viking populations moving into the east maintained control in the Slavic states along the Baltic Sea, Russia, and Steppe regions until they were forced out by invading Mongol armies.

In reading FTDNA’s summary, it appears likely that our Scandinavian DNA a) pre-dates written records and b) came from our English, French, and Irish ancestors.  But wait – what about all those Germans in our line?  Here is an interesting blog article DNAeXplained – Genetic Genealogy (Vikings in Germany).

I know, blog articles are not gospel, right?  😇  Well, I promise to have read other acceptable sources at the library and the blog article I referenced did a much better job than I could at summing up centuries upon centuries of the merging of European and Scandinavian history.  Both the matenal and paternal side of our DNA donors have deeper German ancestry than British Isles or French. So, it’s not so surprising after all. 😉

Comparison of our autosomal donor’s Ancestry DNA (left) and FTDNA (right) ethnicity estimates.  Asia Minor is a region in the Mediterranean.  Note, no hits for East Asia, the likely region where U.S. Native American’s originated from. 
Our Y-DNA donor’s ethnicity results.  Shows many of the same ethnic identities as their sibling’s autosomal results, but now we can almost hypothesize how much of the autosomal donor’s results may have been inherited through the maternal line.  The paternal Rhoades line shows no hits for East Europe but picks up larger traces in Southeast Europe and Iberia.
Just for grins and giggles, my mother’s ethnicity estimate from Ancestry DNA.

What about any rumors that we have Native American ancestry?

Everyone has an “Indian Princess” in their ancestry, right (it’s the running joke in genealogical circles)?  In order to support a theory of Native American ancestry a donor who expects to find only European markers in their DNA results would have to have significant hits from East Asia.  Of the two relatives who graciously gave me DNA samples, neither have those markers.  The crazy thing about DNA is, these results don’t necessarily disprove the legend.  Here’s why:

  1. If the Native American ancestor was a woman, her DNA may not show up in the Y-DNA results.  First, we would need to identify her, second trace her mtDNA descendants, and third test them for confirmation.
  2. For the autosomal donor, if there were a Native American ancestor they would have likely occurred in the early 19th century or later; in our case, 7 generations removed from the donor.  Remember, the results are not great past 4th cousins.  And it would have only been one donor in antiquity whose DNA markers would have become more and more diluted by repetitive European admixtures through the generations. 
  3. DNA results also do not rule out the possibility that a rumored Native American marriage occurred with a sibling of one of our ancestors OR was an earlier or subsequent marriage to a male ancestor.

We may never really be sure.  Just don’t count on applying for acceptance into any Native American tribe.  Personally, I don’t subscribe to our “Indian Princess” lore, but that doesn’t mean we have to stop keeping an open mind.

One final note (and this is my last anti-Ancestry plug), AncestryDNA’s Native American markers are not the marker’s they would like commercial viewers to think (not for the Northern American tribes; Cherokee, Sioux, Pawnee, etc.) Their Native American markers are for southwest U.S. South-central America, and South America (think Inca and Aztec).  There is not enough sample selection for Native American’s from the Northern United States to provide adequate analysis due to a lack of pure living DNA samples, and a reluctance for the Native American tribes to provide samples. See Genetic Testing and Tribal Identity for one of many articles discussing this phenomenon.

Further interesting reading on Native American theories and DNA can be found in the article One wave or many?

Posted in DNA