The Perils of Thrulines

I’ve talked before about the pros and cons of different kinds of hints on the various commercial genealogy sites.

Today I want to write about Ancestry’s ThruLines, which are a DNA hint. When you get your results, if you attach your DNA to your tree, it will look for matches who could be related through various direct ancestors. Here’s an example from mine.

And this is an example of why you need to be careful. On the face of it, we’ve got my PATERNAL 2x great-grandmother, Mary Swan, about whom I previously wrote. Mary married a man called James Lawless. Their daughter Mary is my direct ancestor and I have a number of confirmed DNA cousins through their daughter Josephine.

However, Thrulines has suggested a DNA match of 143cM as potentially being descended from Mary too. There’s a few red flags. Let’s go through them.

• The suggested child is called James Lawless, born in 1891. This would place him between 2 confirmed children but the hint only suggests he is a half-relation. Now, it is of course possible that Mary Swan had an extra-marital relationship to produce this child but here is where wider of the knowledge of the family is essential.
• Mary Swan had been married since 1876. She had a child in December of 1891 with her husband. It was a girl and not called James. Her previous child was born in May 1889. There is technically enough time to have another child in between but it’s unlikely.
• However, I also have evidence from the 1911 census, in which Mary reported that she had had 11 children in total, 7 of whom were still alive in that year. I have already identified all 11 children.
• I already know how this DNA match connects to me. His mother was a first cousin of my MATERNAL grandmother. His surname comes from his father. He’s a second cousin once removed. The Shared Centimorgan Project on DNAPainter comfortably predicts this relationship for 143cM. There are other possibilities but the paper trail also matches this relationship.

• When I review the shared matches between me and this man, I see a lot of people who connect through my maternal grandmother’s family including my mother & her sister and two of their first maternal cousins. All four of those people have cM matches nicely in the range for a second cousin.
• Sideview sorts all the common matches to my maternal side and notably does not include my paternal 1st cousin who is in the database or other matches to Josephine Lawless’s line.

So this hint is solely coming from the name match of James Lawless to my ancestor’s husband of the same name. Though it is a common name, I have investigated the married-in James and do not see a possible second connection.

In summary, please do look at these hints, but make sure you do a full evaluation of them rather than accepting them blindly.