Oct 9, 2020

ThruLines vs Theory of Relativity

October 9, 2020

For the last couple of weeks I’ve been devoting some time to Ancestry’s Thrulines and My Heritage’s Theory of Relativity. Essentially, both are ways to help users determine how they are related to their DNA matches using family trees that the users and their matches have posted on the two platforms. In order to use either platform, it’s necessary to have a DNA test with that company.


For me, there really haven’t been any big breakthroughs using either platform. There haven’t been any big shocks such as non-paternal events lurking in my background to completely change the way that I interrelate with my family. However, it is interesting to see how closely the two platforms line up with what I have researched and believe is my family tree. On the whole, I think both companies do a decent job of using the trees that are posted on their platforms to link DNA matches with the right lineages, but there are some errors, and each company has its strengths and weaknesses.


Based on my experience, I like Thrulines for their big picture format. It’s easy to see who your ancestors are on their layout and then to click onto each ancestor to see how many people you match who descend from that ancestor and exactly how each of them descends. For example, if I look at my great grandfather Charles Fernelius, I find that I have 78 matches through him, and I can see a chart which delineates which of nine of his children they descend from. I can do that for each of my ancestors, and it’s a convenient way to see whether I have distant cousins who have tested on that line or not.


My Heritage’s format is a little less organized, at least it feels that way to me. They provide a list of matches from which you can click through to see a Theory of Relativity that shows how My Heritage believes that each match is related to you. One of the biggest advantages to My Heritage is that, as part of their Theory of Relativity, you can also see triangulation charts which show exactly where on specific chromosomes you and other matches overlap, thus helping confirm that your matches are actual matches.


One of the biggest differences between Thrulines and Theory of Relativity is the size of the pool of matches that the matches are drawn from. Ancestry has a much larger database of possible matches since the numbers of people who have tested with Ancestry is far greater than those who have tested with My Heritage. Because most of Ancestry’s testers come from the United States, Americans will most likely find more matches at Ancestry. My Heritage’s number of testers is smaller, but it does include more Europeans than most of the other testing sites. This is especially helpful for those who have relatively recent immigrant ancestors, approximately from the mid 1850’s forward. These folks will be more likely to find matches on branches of their family who remained in Europe on My Heritage.


The biggest drawback to using either Thrulines or Theory of Relativity is the fact both of them use family trees submitted by testers to determine how testers descend from a common ancestor. This is fine, if the trees are accurate, but in many cases, they’re not. In my opinion, My Heritage has a bigger problem with inaccurate trees than Ancestry does. This is not to say that all of the trees that Ancestry uses are correct; there are many that are not. However, at least on my own lines, My Heritage seems to have many more inaccurate descendancy paths. I have seen other bloggers mention that they feel that the problem is caused because of all the European-based trees where it seems that testers are more apt to conflate people with the same name, particularly in Scandinavia, where patronymic naming patterns mean that a great many people share both a first and last name. I have also noticed that My Heritage is full of errors such as making a child only a year younger than his mother or showing a man born in 1820 married to a woman born in 1740.

I find both Thrulines and Theory of Relativity useful, and I intent to continue using both. They both contain paths that attempt to show how a genetic match may be related to a common ancestor. However, both should be verified because while DNA may not lie, how that DNA got to you and your matches could occur in various ways and may not be through the paths that Ancestry and My Heritage show.


Carol Stetser

Researcher/Director at Large