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I am matched to 8 or 9 different people who all happen to be first cousins to each other, and who also apparently are all my first cousins. They have between 1032 cm’s all the way down to 785 cm’s and between 22 and 35 segments. I know they are paternal matches. The grandparents that make them all first cousins to each other, I do not know, and I can’t figure out how they are connected to me. I’m also matched to some of these matches' children and grandchildren, so I’m almost positive they are not double cousins. How do I figure this out?

My parents were in their mid 40’s when I was born. I'm 47, and all of these mystery cousins are between 55 and 70 years old.

Below are the CMs, total segments, and largest segment, for each one of my matches. A-H all have one parent that are siblings to one parent of the rest. I also am a match for B’s son and B’s granddaughter.

Person CMs Total segments Largest segment
A 1016 39 90
B 999 28 119
C 938 32 128
D 928 31 99
E 859 25 168
F 749 25 162
G 636 22 81
H 532 22 78
I 893 35 87
B's son 496 19 76
B's granddaughter 349 17 71
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  • Are you able to include a matrix in your question that shows the cM match between each pair of these cousins (and include your match to each too)? If so, please just identify them as A, B, C, etc and not by name to comply with our privacy policy.
    – PolyGeo
    Dec 14, 2022 at 4:12
  • Do you have any visible information from non-living relatives that would give you a place to start paper-trail research on their tree?
    – Jan Murphy
    Dec 17, 2022 at 22:05
  • I have the whole family tree for all of these matches. Match B and H, have emailed me lots and lots of family tree info. And explained that they were related to all the other matches as first cousins as well. So, yes I know who their parents, grandparents and great grandparents all are on paper. But I don’t understand how I fit into that tree? It doesn’t match up to who my bio-dad is supposed to be? Dec 17, 2022 at 22:37
  • If you want more hands on assistance solving this mystery then join the Facebook DNA Detectives group. After you join, read the files the group has for instructions on how to request a search angel. They have a lot of volunteers who will be happy to help you solve this.
    – Bill
    Dec 21, 2022 at 16:33
  • So I guess the real problem is, I’m not 100 percent positive, who my bio-sad is? I did eliminate the dad I have on my birth certificate. So that leaves the dad I grew up with. And it’s not looking good for him either. Dec 25, 2022 at 18:36

2 Answers 2

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The Shared cM Project has a new feature where you can enter the data from multiple siblings from the same generation instead of just one, to view the possible relationships to the mystery match (in this case, you).

See the article Shared cM Project | Now Add TWO Testers by Connie Davis, one of the Genetic Genealogy Coaches at the website Your DNA Guide.

This new technique may reduce the number of possible relationships between you and your DNA cousins. Use the data in conjuction with the WATO tool discussed in the previous answer and see what hypothesis you can come up with.

Try to keep an open mind about the dad you grew up with and the dad on your birth certificate. It's possible that the NPE (not the parent expected) event did not take place at the generation you first considered. Think about timelines and locations for your bio mom and your possible dads' moms, and look for times and places in the paper trail to see where things might match up.

You say "The grandparents that make them all first cousins to each other, I do not know..." so if you don't know your matches' MRCA (most recent common ancestor), that might be something to work out first before you try to see where you fit in.

If you need to add more information to your question (for example: once you figure out who their MRCA is), use the edit button under the question to add it.

Update:

In a recent email newsletter, Diahan Southard provided an overview of some of the principles found in her book Your DNA Guide that can help solve problems like yours.

  • Checking the genetic relationships of your matches against genealogical relationships
  • Using Best Known Matches (BKMs)
  • Using Ancestry’s dot system and the Notes field to label matches
  • Using the Leftover Strategy to find matches pertaining to an unknown line
  • Using the Counting Cousins strategy to figure out what kinds of matches will most help answer a question

Even if you don't have the resources to purchase her book or join one of her paid "Deep Dive" webinars, you can visit her site to read the free blog or take one of her free webinars to learn more strategies for analyzing your matches.

Diahan Southard has also given free talks at previous RootsTech Conferences on analyzing matches. Unfortunately the recent reorganization of the RootsTech site has broken the links to the older video libraries, so I can't link to the talks I've viewed. But I do recommend her as a presenter. Her talks are clear, informative, and compassionate.

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This sort of puzzle is exactly what the DNAPainter WATO (What Are The Odds?) tool was designed to answer:

https://dnapainter.com/tools/probability

There's also a Facebook group devoted to users of this tool:

WATO Facebook page

Basically, you create a WATO family tree that includes all of these matches, then create multiple hypotheses as to where you (the target) fit into it (the tool can also generate hypotheses automatically). Any hypothesis you see with a value wildly higher than all the others (10X or more, some say 100X) is almost certainly correct.

The Shared cM tool (also on the DNAPainter site) indicates that those who match you at 900+ cMs are 100% likely to be either your great-aunts/uncles (siblings of one of your paternal grandparents), or your half-aunts/uncles (half-siblings of your father).

You may need to consider the possibility that your father is not his father's biological son. WATO should confirm or reject that possibility.

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