I have written before  about this particular issue, the most recent brick wall in my own family history. Considering the sort of stories I hear about people who struggle to find their ancestors, I have to admit that I am pretty fortunate in most of my family lines, in that I have pretty well-researched lines going back a long way, and could probably get some of them to go back a lot further because of who they are connected to if I so chose to. While some people struggle to find their parents and grandparents, I have seven of my eight great-grandparents pretty well researched. It is, as one might guess, the eighth one that causes some interesting questions. I already noted that there is between 3 and 6% missing Welsh ancestry from that eighth connection, and the possibility of a non-paternal event is something that likely needs to be investigated.
There is, of course, a major issue. Making things difficult is that there are so few people who one could check to find connections. There are only three living adults who share that precise family tie connecting through that great-grandfather, and all of us have had our DNA tested already at ancestry.com, and I have had mine tested at quite a few other places as well. We have no surviving paternal aunts and uncles, and no second cousins from that side of the family, since my paternal grandmother had no known siblings whatsoever, and therefore no nieces or nephews. This is lamentable, but not necessarily surprising, as her legal father died when she was only a few months old, and her mother, who for various reasons is a major historical villainess within our family, never remarried or, to our knowledge, had any other children.
As a thought experiment, I pondered how it would be that such a mystery would be solved. On the one hand, one would need to make sure that the legal father was not the real father. While my official great-grandfather died in 1923 and was apparently buried (according to Find A Grave, which is about as reliable a source as one can get) in Central Pennsylvania where his family lived, he did have plenty of relatives who, at least from what I have been able to uncover, remained living in the same community for decades and may in fact live there to this day. While I have never (for perhaps understandable reasons) found myself connected by DNA to any members of the Filer family, it is quite possible that members of that family have had their DNA tested, and their absence of connection with any of the three members of our family who share the supposed link through that great-grandfather would indicate that there is indeed a non-paternal event worth investigating, and that the reason why there is no Welsh ancestry found in any of us is because there was none, and that we should look somewhere else for our missing great-grandfather.
This has been a bit more difficult of a task to engage in. What we would be looking for is a small segment of people who have a genetic connection to the three of us but who are not related to the Albrights or to the endogamous Lindermans or the Shearers or any of the other known paternal links that happen to be established to be other lines. So far this has been elusive, as all of the cases where I have seen close paternal relatives it has been through one of these other much more fecund lines, rather than the specific line of my paternal grandmother’s father’s family. It would, of course, be far more complicated of a task to manage if the person had been already related through some other means, which let us hope is not the case, as that would prove to be a very difficult mystery to uncover.
It is hard to figure out more ways at present to get a fuller picture of that missing DNA. There are, after all, no known surviving members of previous generations who could share DNA. If, for example, my father and uncle and aunt and paternal grandmother had lived into the age of genetic genealogy than one or more of them may have been persuaded to share DNA and have it tested to better understand that side of the family and its DNA. To be sure, there would have been a lot of duplication because of the close matches with the rest of us who shared our DNA, but it also would have provided a solid basis for triangulating unknown relatives. But much of that DNA is lost, and the absence of people from the last two generations of the family to find a missing person in the next generation above that does not make things particularly easy. One must make do with the resources one has, at least at present, in the absence of our family being of sufficient historical interest for DNA to be tested posthumously.
As a thought experiment, though, two steps appear to be worth taking to solve this particular brick wall. First, rule out the tie with the Filers, if it can be done, through checking people with that particular background. Second, find relatives who fit in that narrow space of being related through that particular great-grandfather and then try to figure out how we could be connected through someone living in the early 1920’s and being connected through the area of Western Pennsylvania where our family was from. If that can be done, it would be a task worthy of a genetic genealogy research project, and probably a fair amount of writing as a result.