Owston DNA Studies: Ancestry Composition of Three Sets of Siblings



This year’s holiday season started a little early for genetic genealogists, as several items came our way.  In November, Family Tree DNA (FTDNA) announced a two-month long sale that certainly jumpstarted some family projects.  Also in November, the first results from Genographic 2.0 from National Geographic were released to some of the early adopting female customers.  The initial male participants received their results in early December.  In addition, the Genographic 2.0 results were available for transfer to FTDNA as well.

Also in December, 23andMe announced that it was dropping its price from $299.00 to $99.00 – making their extensive DNA test available to just about anyone.  In addition, 23andMe updated their Ancestry Painting which originally identified three populations (European, Asian, and African) to a new feature called Ancestry Composition.

Ancestry Composition analyzes customers’ autosomal and X DNA in relation to 22 reference populations.  A customer can fine tune his or her results by comparing his or her DNA to the standard estimate, conservative estimate, or the speculative estimate.  Although liberal in the assignment of segments to the reference populations, I prefer the speculative estimate.


23andMe’s Ancestry Composition features three concentric circles or partial circles.  The inner circle represents the global ancestry.  In the middle, the circle is the regional ancestry.  The sub-regional ancestry is found on the outer circle.  Any blank spaces represent segments that are not specifically assigned to a distinct population.

This new feature will be the focus of this post, but first a little background needs to be provided.

The Owston Autosomal Study

Beginning in 2010, a North American group of Owston descendants (called the Cobourg Line) began testing their DNA through 23andMe.  Although the project initially began slowly, it has grown to 16 participants.  In addition, three Owston spouses have participated bringing the number to 19 in total – although their participation is for reference purposes only.

While there is some debate on the validity of using autosomal DNA in a surname project, we have been able to compare the matching segments of a number of participants that run the relationship gamut from parent and child to that of fifth cousins.  In several cases, the results confirmed three relationships in this family that were in doubt and determined that a fourth was a product of an unreported adoption that occurred 140 years ago.

william_and_frances_owstonWilliam and Frances Wilson Owston

The 16 participants are descended from William Owston (1778-1857) and Frances Wilson (1782-1853) and represent progeny of five of their eight children:  Thomas Owston (1804-1874); William Owston, Jr. (1807-1892); James Wilson Owston (1809-1858); Charles Paget Herbert Owston (1817-1858); and John Gillon Owston (1826-1901).  Only the daughters of William and Frances Owston are not currently represented.

Two of the daughters, Mary Ann Margaret Owston Smith (1819-1909) and Euphemia Owston Smith (1824-1891), appear to have no living descendants.  The eldest daughter, Frances Janet Owston Williamson Sutherland (1815-1902), has living issue and her descendants are being sought to participate in this project.  The 16 participants represent 120 unique relationships among family members.  Since two participants appear to have NPEs (Non Paternity Events) in their ancestry, the number of unique genetic relationships shrinks to 91.

For anonymity purposes, participants are identified with alphanumeric characters. As the project is adjunct to the Owston/Ouston Y-DNA Study, Owston males are identified in the same manner as the other study with numerals (i.e., Cobourg01, Cobourg02, and etc.).  Female participants and non-Owston males are identified alphabetically (i.e., Cobourg-A, Cobourg-B, and etc.).  The sequencing is chronologically based on when the results were returned by 23andMe.

Autosomal DNA, found on Chromosomes 1-22, contains contributions from all of an individual’s ancestors; however, the amount of DNA these ancestors pass to us theoretically halves every generation.  As we get further removed from our ancestors, the contribution of some ancestors’ DNA may be greater than others.  While it is possible to attribute DNA to earlier ancestors, it is generally considered that the limit on most autosomal DNA tracking is at the level of fourth great grandparents or the fifth cousin level.

Currently, none of the fifth cousins in our study have any matching DNA (at 5cM or longer).  While it has also been estimated that there is a 45% chance that fourth cousins will have matching DNA, our study’s 33 fourth cousin relationships only have 17 with matching DNA, which is 51.5% of the total possible 33 relationships.  If we add the two participants who have suspected NPEs, the number of possible fourth cousin relationships grows to 48 and the percentage of matches drops to 35.4%.

Ancestry Composition among Participants

While very little of the DNA that is analyzed through Ancestry Composition relates to the participants’ Owston forebears, we were able to determine the origins of matching segments in the 17 fourth cousin pairs.  These segments were primarily British/Irish, while some segments were listed as Nonspecific Northern European.  With the Owstons hailing from England and the Wilsons from Scotland, these results were consistent with our ancestry.

While the average percentage of shared DNA among fourth cousins is 0.195%, the amount of shared DNA in the Owston autosomal study ranges from 0.07% to 0.77%.  The mean DNA shared among the 17 participants is 0.25%, which is slightly greater than the anticipated average.  With such a small amount of DNA that is shared among participants and the fact that many of the individuals, in addition to their Owston/Wilson components, have a unique ancestry, it is not practical to compare all participants with Ancestry Composition.

Because the Owston Autosomal Project has three sets of siblings, it is possible, however, to compare and contrast these close relationships.   Siblings, on average, will share 50% of their DNA and although they share an identical ancestry, there will be differences because of the 25% from each parent that the sibling pairs do not share.  The project’s three sets of siblings include a trio of brothers, a pair of sisters, and a brother/sister pair.  All seven were born as Owstons.

Sibling Set One

Of these three brothers, Cobourg02 shows as having only a European background; however, Cobourg03 has Native American and Cobourg01 is depicted with Native American, South Asian, and North African ancestries.  The non-European ancestries are very small at only 0.1% each – showing only a very slight or distant ancestry or perhaps even noise and no real ancestry in these areas.  In the case of the Native American ancestry that both Cobourg01 and Cobourg03 share, their mother shares the same percentage and her Native American segment is at the same chromosomal location.


Cobourg03 also shares a large reported percentage of Italian ancestry at 9.5%.  While their mother has 2.4% reported Italian heritage on her Ancestry Composition and has known that her mother’s family spent time in Italy during the 17th century, the larger percentage of Italian ancestry must come from the brothers’ father.  A second cousin (Cobourg06) also has a reported Italian ancestry of unknown origin.


The paternal grandfathers of the two second cousins had a sister whose name was Essa Marcelli Owston.  The origin of the Italian middle name may indicate that some Italian ancestry may indeed come through their great-grandmother’s lineage which is not completely known at the present.

The brothers share varying amounts of DNA with each other.  Cobourg01 and Coboug02 share a considerable smaller amount of autosomal DNA with only 41.00% shared.  Cobourg01 and Cobourg03 share 49.60% of their DNA.  The largest share among the three relationships is between Cobourg02 and Cobourg03 with a share of 50.80% of their DNA.

Sibling Set Two

As daughters of Cobourg01, these sisters show some slight differences and these generally come from their mother’s side of their ancestry.  While their father had some Southern European composition, Cobourg-C shows a larger percentage of this heritage that comes from her mother’s side.


Both sisters have Sub-Saharan African ancestry that also is inherited from their mother’s side.  Since their mother was adopted most of her ancestry is unknown; however, she is aware of French heritage which bears witness in her own Ancestry Composition and the numerous French Canadians which she matches in 23andMe’s Relative Finder and Ancestry Finder features.


The two sisters share 48.70% of their DNA.

Sibling Set Three

Sharing 48.40% of their DNA, this brother and sister combination is related at the fourth cousin level to Sibling Set One. They are also fourth cousins, once removed to the sisters in Sibling Set Two.  Outside of a fourth cousin, once removed (Cobourg-D) who has the project’s largest percentage of British and Irish ancestry composition at 62.5%, the siblings have the second and third largest percentage from the British Isles at 59.3% and 56.8%.


The interesting aspect concerning all three top contenders for British ancestry is that all have a large underrepresented German ancestry.  In reality, the siblings actually have a greater percentage of German ancestry than their British and Irish ancestry and may indicate that reference populations for British and Irish may have a larger proportion of Saxon influence than Norman, Viking, or Celtic influence.


Another of our participants, Cobourg-A, is 50% German.  Although it is her largest identified segment, she is reported as having a French and German ancestry of 26.8%.  Others with German antecedents also appear to be scored lower in this category. Their Germanic heritage may actually be shown in part of their reported Nonspecific Northern European category.

By comparing siblings in an autosomal study, we can see the differences that parents pass on to their various offspring.  It really shows that we are truly unique individuals.

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