A Post About a Triple Relationship

This 5th cousin 1 time removed and I share 111 cM of DNA over 4 segments. The screen shot in this image is from AncestryDNA but this post is not about any one specific DNA site. 111 cM of DNA is unusual for 5th cousins 1 time removed to share (the “Shared CentiMorgan Project” by Blaine Bettinger (cousins with this relationship  usually match between 0-79 cM with an average of 21 cM that are shared).

Of course the numbers at Bettinger’s site are based upon samples submitted by users. There will be exceptions.

This is an exception, but not in the way one might think.

This match and I are actually not just 5th cousins once removed. We are:

  • Third cousins once removed–both descending from my 2nd great-grandparents Riley and Nancy (Newman) Rampley.
  • Fourth cousins–both descending from  my 3rd great-grandparents Johann Christopher Janssen and Elska Tjarks Fecht.
  • Fifth cousins once removed–both descending from my 4th great-grandparents Eilt Gerdes Post and Christine Janssen.

DNA is not an even split from each ancestor, but it is worth noting that these three connections are somewhat evenly split through my tree. Riley and Nancy are my paternal grandfather’s grandparents. Johann and Elska are my maternal grandfather’s great-grandparents (through his mother) and Eilt and Christine are my maternal grandfather’s great-great-grandparents (through his father). I can’t just add the expected average amount of shared DNA for these relationships and conclude that is how much a cousin with these multiple relationships will share with me.

As we’ve mentioned before and as others have mentioned, just because I got half of each of my parents DNA does not mean that I got exactly one-fourth of each of my grandparents’ DNA. One rough analogy is to think that each person has $100 (in $1 bills) as their birthright and will pass $50 of that to their child. Each of my parents shuffled their $100 before passing half of it on to me. Yes, I have half of my dad’s money and half of my mom’s money, but depending upon how they shuffled it, I may not have exactly 1/4 of what my grandparents originally had.

Back to my 111 cM match.

It’s possible that the DNA we share does not even come from the Post family shown in the illustration. Our shared DNA could easily have come from the other two families that we share. There’s nothing to say that just because we share DNA and three sets of ancestors that we have to share DNA from all of them.

 

 

 

Share

2 thoughts on “A Post About a Triple Relationship

  1. I have similar issues, especially in my paternal lines. I have DNA matches that I’m related to 11 different ways. My maternal side isn’t quite as bad, although one set of maternal great-grandparents were second cousins. It really limits the usefulness of tools like clustering when everyone is related to everyone else in multiple ways. I’m tempted to label my biggest cluster “Mitchell County, NC” and just leave it at that.

    • Most of my maternal matches are related on two or three “easily documentable ways.” It’s compounded because the majority of these families are from the same small German villages where they had lived for generations before immigrating. I’m pretty much dumping them in one big cluster.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes:

<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>