Ancestry.com’s ThruLines is a means to facilitate working with DNA matches that have trees attached to them. ThruLines then extends the tree in an attempt to show you how you connect with the DNA match. People are only in your ThruLines if they are:
- a DNA match to you,
- have a tree attached to their DNA results,
- able to be connected to your genealogical tree using the “big ol’ tree” Ancestry.com uses to make connections.
The connection to you and the match via ThruLines is only as accurate as the genealogical pedigree information in their “big ol’ tree.” Because that “big ol’ tree” is made from compiled trees, the information in it may be inaccurate. Because of that the suggested path of connection may not be entirely correct. There may be extra generations, not enough generations, etc. It is also possible that your genealogical connection to that DNA match is through another family and not the one that ThruLines suggests.
The illustration is a good example of individuals who are connected to me, but whose connection to me is incorrect–because it is based on trees of other individuals that contain incorrect information. To make the craziness of the ThruLines as simple as possible to understand, a man named Alexander Neill (son of John Neill shown in the illustration as my 3rd great-grandfather) is in the big ol’ tree three times–twice as nephews of his actual father and once correctly (but not shown in the illustration). These two incorrect Alexanders have lines of descent down to my known DNA matches.
So all the DNA matches in the illustration actually descend from John Neill (my 3rd great-grandfather). None descend from any siblings of this John. ThruLines suggests that the DNA shows evidence that I descend from an earlier John Neill (born in 1773) and his father Charles McNeill. That’s not correct. All my DNA matches (related to this family) are known to come from John Neill my 3rd great-grandfather. The only way a DNA match would suggest a descent from the earlier John or Charles would be if that DNA match descended from the earlier John or Charles–without descending through my 3rd great-grandfather John Neill.
There’s “tree evidence” of the connection between John Neill and his “father” and “grandfather”–using that phrase very loosely–but no DNA evidence at all. The paper “evidence” of the earlier John (and Charles) is weak, weak enough that I’ve not put that information in my actual tree. And there’s no DNA evidence (yet) connecting the earlier John or Charles to me because no DNA matches to me have John or Charles in their tree without also being a descendant of my 3rd great-grandfather.
ThruLines is a tool. Personally I find it helpful to sort out matches that have a tree. But I have to doublecheck those connections.