I posted this query under "general research" but believe this to have been posted in the wrong category. I hope it doesn't violate rules to re-post it here.


I am guessing that maybe half of persons who have taken DNA tests through Ancestry.com have at least a significant amount of Great Britain ancestry. What does this mean in terms of the reported DNA results? The original population of Great Britain (England, Wales, and Scotland) was Celtic, which was little changed by being a Roman province. However, the invasion of Germanic tribes (Angles and Saxons) along with the Jutes from Denmark in the middle ages introduced a considerable amount of DNA from Germany and Scandinavia. This foreign infusion was considerably supplemented by the settlement of Vikings (Scandinavians) especially along the eastern coast of England in the 9th and 10th centuries. The Normans, who invaded and took political control of Great Britain in 1066 and 1067 were also Vikings, but who intermarried with and been partly assimilated by the local French population in Normandy.

How does all of this play out in what is called "Great Britain" ancestry in the reported DNA results? Among Great Britain natives tested, only 60 percent of the DNA in the typical person was "Great Britain" whereas 95 percent of the DNA of the typical Ireland native was "Ireland." Is Irish Celtic distinguishable from British Celtic? Does the non-Celtic early Germanic origin DNA in the typical Englishman show up as "Europe West" and from the Jute and Viking origin DNA show up as “Scandinavia”? Does the “Great Britain" ethnicity measure Celtic DNA? If so, its existence should be strongest in Wales, Scotland and the Cornwall area and weakest in Eastern England, which received both Viking and Germanic invasions and the partial displacement of the original Celtic population.

In my case, my DNA ethnicity estimate is 47% Great Britain, 39% Europe West and 7% Ireland. Excluding my paternal grandmother who was a German native and contributed presumably 25% Europe West ancestry, the breakdown is 63 percent Great Britain, 19 percent Europe West and 9 percent Ireland with under one percent Scandinavia. My material ancestors were overwhelming Scots who moved to Ireland in the 17th century and then to the U.S. in the early 18th century (i.e., the prototype Scots-Irish) and my paternal ancestors excepting my grandmother mainly originated in England with many moving to Ireland in the 17th century and then to Pennsylvania and later Indiana in the 18th century (some as Quakers, which is very good for finding records of births, marriages, etc.), but some also moving directly from England to New England during the “Great Migration” of Puritans in the 1630s. One of the maternal ancestors married a person of German ancestry in Pennsylvania (“Pennsylvania Dutch”) but otherwise all on both sides (especially on my mother’s side where all were committed "Reform" and later "United" Presbyterians) apparently married persons like them in terms of national origin and religion. To my knowledge, none in Ireland ever married an indigenous Irish.

My wife’s ancestry is mainly English both with several (“Jones”, Lloyd” and “Morgan”) of Welsh Methodist ancestry and some who also moved to Ireland before coming to the U.S., including at least one Quaker family, and one ancestor who was “Pennsylvania Dutch”. The DNA analysis reports her ethnic background to be 70% Great Britain, 10% Ireland and only 8% Europe West. It was also 6% Europe East although we do not know of any relatives from there and 3% Finland/Northwest Russia although again we do not know of relatives from there. The DNA analysis suggests she is more British than the average native-born Brit. Is this due to Celtic DNA from the Welsh ancestors? The Europe West component is low despite the infusion of German DNA in the U.S. As in the case of my ancestors, none of her ancestors in their stopovers in Ireland apparently ever married into the indigenous Irish population.

Can someone knowledgeable explain the results of our tests in practical terms of where our ancestors were from? This really boils down to what “Great Britain” means in terms of ethnicity, given the different groups that comprise the population and my assumption that the Celts of Ireland and Great Britain should be one population DNA wise.

Thanks!