Using DNA to find the common ancestor

If you have ever taken an autosomal DNA test with any company, be it Ancestry, 23andMe, FamilyTreeDNA, Living DNA, etc., you will have seen that your results will appear on the company’s database along with a (generally long) list of others users who match your own DNA. Now, I am not a genetic genealogy expert, and all I have learnt (and I am still learning) generally comes from experience and from reading articles & papers, online professional videos and specialised magazines. This said, genetic genealogy is not difficult to apply to your “traditional” genealogy research – if you know how to apply it. Here’s a good example of what I mean:

Some months ago I was contacted by someone in America called Kathryn (not her real name), who appeared among my DNA matches as an (estimated) 4th-6th cousin. That means that Kathryn is, theoretically and at the very closest, a great-great-great-grandchild of my great-great-great-grandparents. Of course, the calculation is based solely on the amount of the DNA that we have in common, which necessarily begs the question “Why do we share this amount of DNA, and not more, or less?”. As I’m sure you know, we inherit 50% of our DNA from our father, and the other 50% from our mother. However, our more distant ancestors’ DNA, starting with our grandparents, is inherited randomly via our parents. In other words, we may get 50% from dad and 50% from mum, but that does not mean that we get 25% of DNA from each grandparent: in fact, as a rule, we don’t. We might, for instance, get 35% of DNA from our paternal grandfather, but just 15% of DNA from our paternal grandmother. That’s the randomness of DNA for you! The below diagram explains the random inheritance pattern of DNA more simplistically.

As I have managed to track down the name and origin of most of my great-great-great-grandparents, I thought that my genetic coincidence with Kathryn was too good to ignore. The first step was, naturally, to ask Kathryn where her immediate ancestors came from. Like me, she has Italian blood, but her ancestors apparently came from Southern Italy, while my Italian forefathers were from a small area sandwiched between the hills of Northern Italy. Not a likely scenario for our presumed nearest common ancestor to have come from. We therefore turned our attention to her father’s family, and this time we seemed to strike gold, as her paternal line has a connection with Galicia, the north-western part of Spain where practically all of my mother’s ancestors lived as far back as the 1600’s.

The next step was to cross-check if our suspicious about a geographical connection were right, and so I had my mother tested so I could compare her results with Kathryn’s. Not only did they share a match, but they also seemed to be more closely related, as Kathryn shared more centimorgans with my mother than with me. We were definitely on the right track.

I then asked Kathryn to share with me some of her recent family history which might help me to unearth a common name which I could follow up. She said her paternal grandfather had been born in Spain in the early 1900’s, and that she had once seen his parents’ names on his birth certificate, which she has since lost. However, there seemed to be some inconsistencies and loose ends with her story when it came to the identity of her grandfather’s father. She said he belonged to a middle-class family who started a transport business which later developed into a bus company. She also said her great-grandfather had died young (she had even seen his grave in Galicia on a visit some years back), and that his widow, who was of lower birth, had been turned away by her in-laws and had left Spain for America, leaving her son to be brought up for foster parents.

With the names she was able to provide me, I searched online newspaper archives to see if I could find any reference to either Kathryn’s grandfather or his parents, and luckily I found an obituary for a man who died in 1915 whose name matched that which Kathryn had provided. I immediately sent for the man’s Spanish death certificate, but when I received the document I made a very curious discovery: the man, called Manuel, was unmarried, so there was no reference to a wife, nor to any children. I again cross-checked with Ann to see if the story she had told me may have been wrong, but she was sure we had the right man. It wasn’t difficult to track him down in the Spanish census at the turn of the century, and this helped me to prove that Kathryn’s story about a family-run bus company was absolutely spot on. Luckily, both of Manuel’s parents were listed, as was their respective place of birth: the father was born in the Castilian province of León, the mother in Madrid. So it was clear that the family did not have any immediate genetic ties with Galicia, the area w were focusing on.

My attention then shifted to the mother of Manuel’s child, Josefa, whose full name was not very clear to us. I searched high and low for a birth certificate for their illegitimate son, to no avail. Unfortunately Kathryn’s efforts to retrieve the document she had seen years before were not yielding any results either. It was only then that we decided to try a different source, and we applied to the church archive for a baptism certificate. Their response was positive, in that they had found a corrected baptism certificate, issued in the 1970’s (in other words, some seven decades after the child had been born) where his parents’ names were mentioned. The document not only confirmed the father’s identity (it was, incidentally, the man called Manuel whom we had previously been looking for), but it also served to confirm the mother’s full name: Josefa Adega López (the last two being her two surnames, as is the Spanish custom).

Armed with a full name, I decided to track Josefa down in the census; her son’s baptism certificate confirmed she came from Ferrol, the same city as some of my ancestors, and so I decided to look her up. I was somewhat dismayed by the fact that she too seemed to be illegitimate, as I was able to find her living with her elder sister and their single mother in the 1887 census, when Josefa would have been about five years old.

The fact that Josefa was illegitimate naturally opened the possibility of never actually finding out who her real father was. But before committing myself to searching aimlessly for a purported father, I asked my grandfather’s only surviving sister to take an autosomal DNA test too. The reason for this was that she was my theoretical link to Kathryn’s family, but as of yet I had not proven this much other than by testing my mother. The results confirmed that my great-aunt and Kathryn were indeed fairly closely related (still within a 4th-6th cousin relationship), and although I still was not 100% sure of how we are connected, at least we knew our link came via my maternal grandfather’s family.

Unfortunately my application for Josefa Adega López’s birth certificate has been unsuccessful: she was either recorded under a different name, in a different location, or she was not registered at all. Church records in the area are noticeably hard to come by, and so for the time being I have little to go on via Kathryn’s family line.

Although I do not think I will be able to confirm the link between our two families (not, that is, until there is sufficient documentary evidence to prove it – and, as this is a case of an illegitimate child, I am not raising my hopes too high), I decided once again to go down the genetic path. (There’s a family tree chart at the end of the article which will help you follow the story as I explain it.)

As Josefa was born in 1882, I laid out who of my family could have actually “done the deed”, and I found a rather curious set of options: my own great-grandfather was born in 1879, and so he would have been too young to father a daughter at the time. His elder brother were also too young to become fathers in their own right, BUT their father (my great-great-grandfather) could easily have fathered Josefa out of wedlock. I just hope for my great-great-grandmother’s sake that he didn’t!

The other option, which is tantalisingly suggestive, is my great-great-grandmother’s only brother, Juan. As Juan was born in 1836, he would have been 46 at the time of Josefa’s birth, so he could well have been her biological father. He was, at the time, still single, and he may well have had an affair with Josefa’s mother. However, in about 1890 he decided the time had come for him to marry. His choice of bride was none other than his own niece Flora, by whom he would go on to have two children.

Now, my grandfather’s family is not very extensive, and I know very few relatives on that side whom I could ask for a DNA sample. One of them, curiously, is a descendant of that uncle-niece marriage, and so I have decided to ask her to have a DNA test. I may also ask another cousin who is descended from another brother of Flora’s. If Flora’s descendant’s DNA results show a much higher DNA proportion with Kathryn than with me (Flora’s descendant, after all, would be related to Kathryn not only via Flora herself, but also via Juan), then we may just well have found the identity of Josefa’s biological father. If, on the other hand, both Flora’s descendant shares the same amount of DNA as me and our other shared cousin, we may well need to take our documentary and genetic research  a generation back. Only time, and DNA, will tell if we are on the right track!

Either of the two men in a red box may have fathered Kathryn’s great-grandmother. My third cousins’ DNA may prove it.

This entry was posted in DNA, Galicia, Genealogy, Genetic Genealogy, Illegitimacy, Spain. Bookmark the permalink.

3 Responses to Using DNA to find the common ancestor

  1. Jill says:

    Thank you for this. Really fascinating and intersting the way DNA has helped move your findings forward. And brilliant you have older family members who will take the DNA test.

  2. Luanne @ TFK says:

    You are lucky she was willing to cooperate with you. I haven’t made a connection that interested yet.

  3. Marilyn says:

    As I periodically look for clues about Josefa Adega Lopez, imagine my delight this morning when I struck a match with this article! As it turns out, it is you Daniel, and I presume I am Kathryn. 🙂 Please feel free to use my actual name, that is fine. Btw, what I was looking for today was to follow up on a clue I hurriedly jot down a few months ago shortly after my mother’s death. I put the note in my handbag and forgot all about it. This morning I read it and it started there was a Josefa Adega Lopez (what are the odds of the same name?) who arrived on the Saratoga in 1912 as a maid to the Roca family who took up residence in the Hotel Astoria in NYC. This confirms another family story that Josefa had been working as a maid for another family with my maiden name, and became pregnant by the son of said family. Whether they were in love or not, who knows, but she was rejected by them. My grandfather, her son, was born in 1902. When Josefa could no longer afford to care for her son she left him with another family until she could send for him. She was under the impression that America was literally paved with gold, as most of our ancestors thought when they came to the US. This adoptive family continued to care for my grandfather until he came of age and came to the states to reunite with his mother. Our family kept close ties with his adoptive family with visits and correspondence to Spain until the last of my ‘cousins’ died in 2015. I asked that cousin if he remembered any family history about who my grandfather’s natural parents were and how they knew his grandparents who raised him, but my Spanish cousin knew nothing. I was thrilled to coincidentally find my great Grandfather’s grave when I returned to Spain in 2016, as it further confirmed our family story that he died quite young.

    As an aside, my father, who did meet Josefa and had a grandmother/grandson relationship with her in the NY region where they lived, told very colorful stories about Josefa. One, that she read tea leaves and tarot cards. This fascinates me as I have been reading the cards for over forty years and hadn’t known she had also until about fifteen years ago. I mention this because we not only seem to share blood with our ancestors, but also share common interests with them. It’s endlessly fascinating.

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