Why Five of Erasmus’ Descendants Aren’t All Matches for Each Other

I’ve changed the names of the submitters to protect their identify.

A, B, C, D, and I descend from Erasmus Trautvetter, born about 1770 in Thuringen, Germany. His descendants are documented in an 1870-era estate settlement in Hancock County, Illinois, and in church records in Thuringen. A, B, and I all descend from Erasmus’ great-grandson George Trautvetter (1869-1934) and his wife Ida Sargent (1874-1939) through Erasmus’ son also named George (born 1798). C and D descend from two different children of Erasmus.

We’ve all tested at AncestryDNAA and B and I are relatively close matches (to be expected given our relationship). C and D were more distant matches to me.

The matches that I shared with A, B, C, and D are as follows:

A–shares B and C with me

B–shares A and C with me

C–shares A and B with me

D–shares nothing else with me

On the surface that may seem strange. All of us are descendants of the same couple and yet there are two “pools” of descendants: A, B, C and me…and D and me.

We’re going to simplify things just a little bit to make the visual easier to see.

The most likely scenario stems from the fact that all of us do not inherit the same genetic material from our parents. After all, we receive half our DNA from our mother and half from our father. We can’t get a complete set  from each.  Those who share grandparents will not have the exact same set of DNA from those grandparents. There will be pieces that they share, but they will not have the exact same set of DNA from each grandparents–there will be differences.

At the risk of oversimplifying, let’s just concentrate on two pieces of Erasmus’ DNA. We will call one piece 1 and the other piece 2. Son Henry only received piece 1. George received pieces 1 and 2. Daughter Ernestine only received piece 2.

Piece 1 passes to Henry’s descendant we are calling descendant C.

Piece 2 passes to Ernestine’s descendant we are calling descendant D.

Pieces 1 and 2 pass to son George’s descendant George (born in 1869). For some reason, George (born 1869)’s descendants A and B only received piece 1. George (born 1869)’s other descendant (me) received piece 1 and 2. I got the lucky DNA.

That’s why A, B, C and I match and why D and I match, but why we all don’t match each other. It’s because we all don’t share the same DNA. It’s also remotely possible that D and I are related on a non-Trautvetter line, but since D and I share no other matches that doesn’t seem likely.



3 thoughts on “Why Five of Erasmus’ Descendants Aren’t All Matches for Each Other

  1. Thanks for the explanation . It really helps to explain why you can be related but not have a 100% match in DNA, especially to those who are looking at DNA from a mathematical perspective rather than a genealogical one.

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