Not knowing my father, the shared matches that don't match close maternal matches should lead to him, right?

+4 votes
Not knowing anything about my father, when I click on some 2nd, 3rd, 4th or further away cousins and hit shared matches, in some cases my close family (granddaughter, maternal half brother), maternal family first cousin do not show up.

The only conclusion I can come to is that either or connection is far back in history, or they are from his side.

Not having any information on him, the only hope I can see is that a close family relative of his or mine from him, (sibling, first cousin) shows up in a DNA match.

The closest so far is a 3rd cousin who is 192cms and 9 segments and shows no matches to my maternal matches, but matches a  lot of other matches with less cms that don't either.

UPDATE, 1st or 2nd cousin 370cms, 21segments, shared with my granddaughter, me ibviously, but not my maternal half brother, or maternal 1st cousin. So where does this lead us? I am trying to make contact.

Any suggestions?

in Genealogy Help by James Brooks G2G6 Pilot (407k points)
edited by James Brooks
Here's a tip, besides: A match from 300cM->575cM is normally a 1C1R (a child of your 1st cousin). On your dad's side, that could help a LOT.
Thanks Frank, please see my comment farther down.


2 Answers

+6 votes
Best answer
It sounds like you're on the right track.

Really, your maternal half-brother is the key. You will BOTH match ALL your 2C1Rs (2nd cousins, once removed) on your mother's side, and most of your 3Cs. Anyone over about 90cM who DOESN'T match him is definitely on your dad's side.

How many cMs are we talking about?
by Frank Stanley G2G6 Mach 6 (64.4k points)
selected by James Brooks

But I should know better than to say "definitely" - there are "curve balls" that can happen. Even if you and your half-brother BOTH match a 2C, there's about a 1-in-300 chance that his cM lies below 20cM, and he doesn't show up on a "Shared Matches" list, even though he matches. For 2C1R, it's 1-in-30, and for 3C it's 1-in-5.

Another thing is that if there are people intermarrying on your B-dad's side (for example, if his parents were 2nd cousins - stuff like that), or endogamy, it can throw the numbers off (they get higher).

So there's always something to be cautious about, but normally the high cM matches that your half-brother doesn't match are going to be your B-dad's.

BTW, the chance of you both matching 2C1R or closer is practically 100%, but that drops to about 90% for 3C.

Oh, and the maternal 1C is good to use too, just not AS good. The granddaughter has both sides, so is not useful at all in the discrimination. She's two steps more removed from all your relatives, so she won't match everybody you do for that reason on BOTH sides.
The closest I can find so far that meets that criteria is a third cousin who is 192cm across 9 segments. The shared match does not match any of the matches on my maternal side. So this should be the starting point.

That third cousin is surely on your father's side. Which company did you test with? If you tested with Ancestry, upload your raw data to Gedmatch and MyHeritage, in case a closer match is lurking there.
You may need more matches. To find more matches, add your data -- and your half-brother's data -- to Gedmatch, if you haven't done so already. And you and he should test at additional companies.
Thank you Jessica, I'll do that.

Hello Ellen, this seem to be the general concensus, I'll definitely try this.

Thank you


Despite it being in the "3rd Cousins" category (this is on AncestryDNA, right?), be aware that 192cM is most likely at the 2C level. There's an outside chance of it being a 2C1R level, too, but that's about it. Ironically, it is almost certainly NOT a 3C - that's just how AncestryDNA does things.

If you tell me how good a match your granddaughter has to that person, we might be able to tell which level it is.

Any other interesting ones? That one probably only represents one of your paternal grandparents.

I use the term "level" here because cM is a measure of how much DNA you share and there are typically several relations that share the same amount of DNA. As far cM go, 2C = H1C1R = 1C2R and H2C = 2C1R = H1C2R. (where "H" is for "half-", "C" for "cousin", and "R" for "removed". "Half-" relations are unusual, so it's probably either the 2C or 2C1R, but that's another "curve ball" that can show up that's good to be aware of.

* The hardest part about downloading a copy of your test from AncestryDNA is knowing to click on "Settings" near the upper-right corner of the main DNA page. It's a compressed file, and the key thing is to NOT to try to decompress it - GEDmatch uses it "as is". GEDmatch can take a day or two to process. There aren't tons of people on there, unfortunately so don't get your hopes too high, but you might get lucky.

* I think FTDNA is the second biggest outfit, as far as testing. If I recall correctly, you can upload for free, and full functionality is a one-time fee of $19. But don't quote me!  wink

Good luck! 

New news, a 1st,or 2nd cousin, 370cms 21segments, matches my granddaughter, me obviously, but no my half brother and my maternal first cousin. So where do we go from here, I am trying to make contact now.

Thanks again

That's great!  You need to make contact with that person and also the match that looked like a third cousin. Find out what they know about their ancestry and construct family trees for them. (You may have to do a lot of the research...)
370cM is almost certainly a 1C1R, with a small chance of being a super-strong 2C match. It could also be a half-1C.

Since you're a grandparent, I'd guess that it's probably a child of a paternal 1C.

I would think that somebody that close would want to know what you're doing on their list! That being said, sometimes they don't understand, or they already know but don't want to talk about it, or they simply never check their messages. Don't take it personally, if you don't hear back. Try again, every so often. I think of it as a sort of "message in a bottle".

If they don't have trees, or don't respond, you can try looking at the shared matches you have with them. Chances are SOMEBODY among them has trees, and you can try to puzzle out what all those trees have in common. Also, maybe you can find someone who will talk to you, who has some inside info. Comparing notes on how many cMs you have vs people you both match might also be illuminating.

Oh - there's also a group here called "Adoption Angels" who specialize in this sort of thing.
Hello Ellen and Frank, both great comments and I'm working on both of your ideas. Have come across another ,one, 331cm, 21 segments no maternal and the 370 is a shared match.

Guess I've got my writing work cut out for me.

Thanks again for all the help, I had already  written an appreciation piece in here for all the help in finding my maternal family, I guess I'll have to do it again for the fraternal help.

You're very welcome!

Say ... if I'm right - that 330cM & 370cM are children of one or two of your biological 1st cousins - those two should be related to all your matches on that side. If 192cM is a 2C, they would be 2C1R (or closer) to 330cM & 370cM, should have a match with them, with about a 95% chance of those matches showing up on a shared match list. It's just another thing you can easily check for yourself, to see if this theory is working.

If this works, the process repeats! Shared matches with 330cM & 370cM means a match is on your father's side. But if such a match DOESN'T also match 192cM, then it might mean that it corresponds to a different biological grandparent than 192cM (if it's a reasonably strong match).
Good morning Frank, (it's 09:30 here), the 192 does not show up on both 331 and 370, but does not show maternal relatives in shared matches. These country folk are amazing.

As always thank you very much,


P.S. I'm a member of the Adoption Angels, but inactive at the moment due to a family illness.
+4 votes
I use's DNA sharing table any time I work with DNA.  Scroll down a page or two and you will find it.
by Julie Kelts G2G6 Pilot (336k points)
Thank you Julie, I'll try that.


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