In a previous post talked about E’s husband the unknown bigamist, and I am pleased to announce that this bigamist is now known. This presents a unique opportunity for me to share how to find unknown grandparents using DNA, especially when traditional genealogy methods (like locating a marriage certificate) have not been successful.

E’s grandchild D shared their DNA results with me, along with a possible last name. Since D has only done DNA with Ancestry and does not have an subscription to the family tree/records side, they cannot see the family trees of their matches. If this is the case for you, you should sign up for a Free Registered Guest Account. This should let you see the pedigrees for matches with trees, although you still will not have the option to see the full family tree.

Naturally, the first thing I did was look through the available family trees for the last name D gave me. I didn’t find any matches with the last name, but I did find a similar one so I took that last name to a newspaper search site (a subscription that came with my Ancestry subscription) and gave it a go. If the man was a bigamist, there had to be a news article about him, right?

THERE WAS.

Not only did the newspaper article list this man, C, as a bigamist, it also gave his alias, the surname that D had given me. This had to be the guy, right?

Here’s an important tip- follow the evidence. In all cases of unknown parentage, it’s important to gather as much evidence as possible and make sure you have a rock-solid case before making conclusions. It would be really easy for me at this point to say that this man is D’s grandfather but the newspaper article is just the beginning. It’s unfortunate that shows like CSI have exaggerated the conclusions one can make with the evidence, but at least following the evidence rather than what we want the conclusion to be is emphasized. So, what did the evidence say about D’s relationship to C?

The next thing to figure out is how D and their matches were related. How did C fit into picture? I went back to the family trees. Two of the matches listed C as their grandfather. Since they had different grandmothers, however, they would be half cousins to D. I put the amount of shared cMs of each match to D in this tool by DNApainter and lo and behold, it fit that they could be half cousins. Interestingly, Ancestry had put these matches in the category of second cousins. That means that you cannot rely on what any testing company tells you about how you are related to someone. The testing companies base their estimate regarding the relationship one shares with someone on the amount of shared cMs, not on any knowledge they have about how they are actually related. That means that your best bet when trying to figure out your relationship to a DNA match is to use the dnapainter tool.

I wanted more evidence. I found another match, this one also had C in their tree but as a great-grand father. That means that they would be a half first cousin once removed to D. Again, I put the total cMs in the tool, but this time it did not come back in the correct range. I looked at the tree again. C shares the same name as his father. The match’s great-grandfather was not C, but C’s father. That meant D and this match were second cousins. The amount of DNA D shares with this match is consistent with second cousins. Phew!

There is now a lot of evidence to support the fact that C is the Unknown Bigamist, but I still don’t feel like I can say that I am 100% certain that this is D’s grandfather as they would on CSI. Finding other half, second and third cousins would continue to add to the body of evidence, however, if any evidence were to come around that disproves the idea, I would have to take it into consideration. Also, if this were an episode of a TV show, the case would be closed and the theme music would start playing. The real investigation is only starting. Who was this man? How did he meet E? Why did he try to pull off more than one marriage? We have found one answer, and with it comes a lot more questions. Hopefully by contacting his new-found half-cousins D can sort some of this out.