Is my father and his 1C actually half 1Cs?

+5 votes
414 views
Is my father and his 1C actually half 1Cs? That is my theory, anyway.

My father shares approximately 493 cM (18 segments) auDNA and 57 cM X DNA with his 1C, Les, their mothers were sisters. Also, mtDNA confirms they are related on their direct maternal line. The auDNA is on the low end of the range of a 1C, enough so to make me question it. I made a thing: https://dnapainter.com/tools/probability/view/b1e84a1caf7556a1

My father has 2 matches on his mother's side that do not match with Les. One, John, matches my father at approx. 464 cM (18 segments) auDNA and 19.89 cM X DNA. Another, Mary, matches my father at 319 cM (12 segments). I don't know how much X DNA is shared with Mary because this match is on MyHeritage and they don't show X. After building their trees, I've discovered John and Mary have a common ancestor, they are 2C1R. I made another thing: https://dnapainter.com/tools/probability/view/f48d38710a94a2f1

So how can my father's first cousin not share any DNA with John or Mary? My conclusion is that my father's mother had a different biological father than Les' mother and the matches with John and Mary point to the missing mystery sperm donor.

Thoughts? Am I looking at this correctly? Did I ignore anything?

Thanks in advance to ideas, thoughts, confirmations and rejections!

NOTE: I am purposely NOT adding his profile to the question as I DO NOT want this question showing up on his profile. Thanks!
in Genealogy Help by Allison Mackler G2G6 Mach 6 (64.0k points)

3 Answers

+5 votes
As I understand it, every time a child is conceived, a new combination of DNA is drawn from the "gene pool" of their parents.  The child cannot get a gene that the mother or father didn't have -- but the child CAN not have a gene that the mother and father had.  So with biracial children you may have one who is very dark and a sibling who is not.  Or when you get your results from Ancestry.com, you have "Northern European" genes and your sibling does not.  So there may be less than meets the eye in your review.
by Jack Day G2G6 Pilot (462k points)
Jack, thanks for replying!

Yes, this is definitely true! :) This can be seen visually in my sister and I. I have olive skin, dark brown hair and brown eyes, taking after my father's Jewish side of the family. My sister is platinum blonde, blue eyes and pale skin, taking after my mother's side. Autosomal DNA is so interesting that way.

There are some really good statistics out there though that tell us how much DNA we /should/ share with a cousin based on relationship. If two people are 1C or half 1Cs, they have to share DNA, there is no chance of them not sharing DNA. If they didn't they wouldn't be 1C or even 2C.

I personally love the shared CM chart on DNAPainter as I'm very visual and you can click on a relationship and see the histogram of the data collected, which is also helpful in seeing outliers that make you question the relationship. Which is what made me question that my father and his 1C are not really 1Cs. On the histogram, the amount of auDNA they share is a significant outlier, which makes that relationship improbable. It's more likely that people reporting DNA that low for 1C are mistaken about the relationship and have an NPE, as I believe is my situation which resulted in the statistical probably showing up as 1C.
+10 votes
I think your conclusion is right, assuming that you are sure John and Mary match on your father's mother's side. Did you test his father and phase? if not, what makes you so confident? My thoughts:

Note: there are no documented cases of relationships equivalent to 2nd cousins or closer not appearing as matches. Once you get to 2nd cousin once removed, it is possible but very unlikely. At 3rd cousin, it's about a 10% chance.

It looks like your father's mother's parents were Harold and Emma? I'll go with that. If you are sure John is on your father's mother's side, then John would have a common ancestor with either Harold or Emma. Let's say they are on Harold's side.

According to the shared cM tool, your father and John are virtually guaranteed to have a relationship that is genetically equivalent to 2nd cousin or closer.  That means John's relationship to Harold would have to be equivalent to 1st cousin or closer. If Harold is Les's grandfather, then Harold's relationship to John would also be virtually guaranteed to be equivalent to 2nd cousin or closer. So John and Les would have to show as matches.

If John's match to your father were a little weaker, even at the level of the match to Mary, then there would be a very slight loophole that gets you out of this (but still *super* unlikely to be the case at the 319 cM strength you reported between your father and Mary). Combining both the match with John and with Mary, I'd say it is undoubtable that whichever of Harold and Emma was the match with John and/or Mary is not an ancestor of Les.

Where to go from here? I wouldn't assume this casts a pall on Harold and Emma's relationship. Either one of them could have had a child as a teenager, say, before they met. So I wouldn't assume the incorrect parent is Harold. I'd look at John and Mary's common ancestors (Thomas and ?) and see if they or their children ever lived very close to either Thomas or Emma. Unless all of these people in both of the trees you linked lived in the same vicinity, I think geography is the key.
by Barry Smith G2G6 Pilot (292k points)
edited by Barry Smith
Barry, thanks for your reply!

I am sure the matches are on my father's mother's side because the matches share X DNA. Men do not inherit X DNA from their fathers. My father's X DNA match with John could come from either of his maternal grandparents. Correct?

I am comfortable with your statement that at the relationship between my father and John and Mary, as defined by the amount of DNA they share, means that it's improbable that Les does not also share DNA with them unless there is an NPE. Sad, but resigned maybe is a better description. I am not looking forward to this conversation with my father as these are his favorite grandparents and he talks about them all the time.

Yes, my father's maternal grandparents are Harold and Emma. Since my father and Les share auDNA, X DNA and mtDNA, then it's clear that if there is an NPE and that it is definitely with Harold, not Emma. Do you agree?

My father's mother  (b. 1921) was eleven years younger than her sister, Les' mother (b. 1910). Harold and Emma were married until Harold's death and she did not remarry. They lived in The Bronx, as did the ancestors of John and Mary. Thomas, the common ancestor of John and Mary, was their immigrant ancestor, from Ireland. Harold's ancestors are older Quaker New Yorkers. Emma's ancestors were 1880s immigrants from Germany. I think the general proximity also helps lead to confirming this theory, although NYC is huge! I do need to do more specific location research to narrow it down more than that though as Thomas had multiple sons.
I was more concerned with the size of the X-chromosome match. Most people set their threshold for comfort with X-matches higher than that for autosomal DNA. I hear about some people who set it at 20cM or higher.

But now that I think about it, which I never have before, this is probably more to do with the common ancestor providing segments being on average more generations back than when looking at autosomal matches of comparable cM. It's more about not wasting your time hunting for an ancestor 500+ years back than a concern for false matches.

I have never had any useful X-matches before, so I hadn't considered it, but your father and John cannot be false matches -- at least in the form they take in autosomal DNA where one or both's matching segment is actually jumping between the maternal and paternal chromosomes. That can't happen when comparing two men's X-chromosomes, so I agree, that 19cM must be a legitimate match and so the match to John must be on your father's mom's side. I missed that you had compared mtDNA, so yes, it must have come to their mothers from Emma, and Harold is the mis-match.

Just to reinforce this: full sisters would have one copy of their X chromosome identical, since it came unrecombined from their father. You would expect on average for full sisters to share half-of the other X chromosome they got from their mother. So two sons of full sisters should share roughly 75% of the X-chromosome, which is about 196 cM. So the expected amount shared is about 147cM,  *far* greater than that shared by your father and Les. If their mothers are half-sisters, then the still share about half of their maternal X-chromosome but should share about none of the ones they got from their different fathers. You would expect then the sons to share roughly 1/4 of an X-chromosome on average -- about 49cM. The 57cM is very in line with that.

What makes you think it is your father with the NPE, and not Les? Can you rule out Thomas and his wife being close kin to Harold?

Definitely do the specific location research! I hope the answer becomes obvious. CeCe Moore seems to make it seem like it always does on her TV show, but maybe they are picking and choosing the best cases.
Agree with Barry's analysis but it's also perfectly possible that the sisters' fathers were completely unrelated and they just got a higher than average share.
I think that was the conclusion in my analysis. Allowing Allison's father's father to be a sibling or cousin or something of Les's mother's father throws an extra wrench in things, but could explain why her father and Les are on the high side for half 1st cousins. But as you said, they could be completely unrelated and by chance, the match just ended up stronger than is typical for half 1C
I attended a good webinar a year or so ago about DNA comparison and false matches. It was very interesting to learn the probability of a false match on the X chromosome is higher than with auDNA. I tend to use 10cm for auDNA and 20cM for X DNA. But in this case, it was the size of the auDNA match for both John and Mary that made me investigate. I didn't even notice the X DNA until I painted the matches in DNA Painter! LOL! I also felt it wasn't a false X DNA match given the circumstances. It also made me readjust my thinking on X DNA. My father only has a few at all the companies that he's tested or I've uploaded his results to, but I definitely shouldn't ignore any of them, especially in conjunction with more significant auDNA matches. It's interesting that you haven't had a lot of X matches either. Even my mother doesn't have a lot of X matches.

Thank you for the data analysis! Honestly, I hadn't even looked at or figured out whether the amount of X DNA my father shares with Les was appropriate for 1Cs. I was too focused on the amount of auDNA. So that was a miss on my part. Lesson learned!

See my answer to Frank (below) about the match that Les has on Harold's side of the family and let me know what you think. A 20cM match between Les and his 2C2R through Harold led to the assumption the NPE was my father's maternal grandfather, not Les' maternal grandfather.

The location will definitely be harder than the cases on CeCe's show! I'm looking at people that all lived in the same borough in NYC, unfortunately. But maybe I can find one of Thomas' sons that lived much closer, or worked nearby or something, to Harold and Emma. It's funny how in such a large city, people lived, worked and married within a block or two. I don't /think/ they attended the same church, assuming Thomas' family was Catholic, but I probably should confirm that. I'll have to ask my father if Harold was religious at all, he was descended from disowned Quakers. I know Emma's family was Lutheran.

Thank you so much for your great insights!

Matthew & Barry,

I haven't found any evidence of the possibility of a possible relationship between my father's paternal and maternal sides, but I obviously haven't found all my ancestors.

My father's father, Frank, is Jewish, which makes separating matches really easy.

Harold is descended from a long line of Quakers in New York. Les is not Jewish and has no Jewish matches.

Should I be looking for a possible relationship between Frank and Harold despite evidence to the contrary?

+8 votes
It sounds like you're generally on the right track, to me.

To clarify, though, you're saying that John and Mary are 2C1R to each other, right? Really, from that second graphic it looks like it's really 1C1R, but the important information is that Mary is a generation below John, and their common male ancestor is Thomas. Certainly, it looks like John is at the 1C1R level, and Mary at the 2C level.

In your situation, that probably means the relations are H1C and H1C1R, respectively ("H" indicating "half-"). In other words, your dad at the "Hypothesis 11" spot. I don't put much stock in the statistical calculations of DNApainter, in terms of actual percentages, but it seems like they can often point you in the right direction, nonetheless.

I guess the idea is that we know John is on your mother's side because of the X match. Well, the John's mother and your dad's mother would be half-siblings, and each have an X from their father, Thomas, parts of which would be passed along to their sons. It all makes sense.

Sure sounds to me like this Thomas is your dad's biological maternal grandfather! You could go crazy trying to dream up some other scenario to try to explain this. The "proof or the pudding" is in the extended relatives. Does Les have matches to his maternal grandfather's family, while your dad has none (except maybe as low value matches that might indicate a relation through an unknown path)? Does you dad have a bunch of matches to Thomas' relatives, beyond John and Mary, that Les doesn't? I would think that would settle it pretty conclusively.

As you start to look into your new-found biological relatives, and discover more and more DNA matches to them, any reservations you have about this will gradually fade away.

493cM is in the bottom percentile for a 1C, even on AncestryDNA, and it sounds like this might be on GEDmatch (which should be a bit higher). The average number of segments for a 1C is about 37. For a H1C the average cM is a bit over 400cM, and the average number of segments more like 22 - everything fits!
by Living Stanley G2G6 Mach 9 (91.2k points)
Oh, and check to see if your dad DOESN'T match relatives of Thomas' wife, too.

But watch out for possible intermarriages that could throw everything off.
Frank, thanks for replying!

Brain fart on the cousin definition. I was looking at the shared cM chart, on DNA Painter, while too tired! :) Yes, you are correct, John and Mary and 1C1R. John's grandfather is Mary's great-grandfather.

I reviewed all the hypotheses and also felt like #11 was the most likely, probable scenario. Since my father and Les do share DNA, then that excludes my grandmother being a full child of one of Thomas' descendants or her being a half-sibling of John or Mary. Other hypotheses that would make my father the child of someone born in the 1880s also don't make sense. So that eliminated a lot of the choices, besides that probability score being so low. I'm glad that you came to the same conclusion.

I definitely have been trying to dream up scenarios! LOL! :) It's not that I don't want to believe it, but 1) like any science, it's good to get theories reviewed 2) I was diagnosed lupus a few years ago and the disease and all the meds I'm on have affected my cognitive function and I really doubt myself a lot these days 3) I also really don't want to tell my father because these are his favorite grandparents and he'll be really disappointed. So I really wanted to make sure what I was thinking was correct.

I had uncovered, a few years ago, that Harold, my father's mother's father had a different father than we all knew about. His surname was Pitman, which was my grandmother's surname. But it turns out he was born to William Kinzey, who died when Harold was very young and Harold's mother remarried, changing Harold's surname to her second husband's name. This was news to my father and his cousins! William Kinzey had many children with his first wife. A descendant of William's first wife, who would be my father's and Les' half 2C2R, found me online and we shared information. He did an Ancestry DNA test and uploaded to GEDMatch and my father does not match him, but Les does, at 20.6 cM on one segment. That relationship, half 2C2R, could result in zero shared DNA. So this doesn't help too much. Most of Les' matches don't have tree, don't communicate and don't match on X, so I've struggled to determine any other Kinzey matches. Should I focus more time on finding Les' Kinzey matches to determine if any match my father?

My father does have a bunch of matches to Thomas' relatives. There is one match on MyHeritage of 170 cM, from Spain, that triangulates with Mary, and after bringing Spain into DNAPainter, they also have a large segment overlap with John. There are some other matches that triangulate with John or Mary as well, I have ten besides John and Mary in a match group on DNA Painter. Another one, that is ICW Mary, is a 42.6 cM match from Australia that also overlaps with John in DNA Painter. Australia carries that same surname as Thomas and Australia's ancestor is from the same town in Ireland that Thomas is from, but emigrated to Australia, instead of America. I haven't found their shared ancestor yet though. I'm going to have to learn how to research in Ireland! Of all the matches of my father's that I can confirm match John and/or Mary, none of them overlap with Les. Do these additional matches change your conclusion at all?

My father tested at 23 & Me, which is where he matches John. I uploaded my father's test results to MyHeritage, which is where he matches Mary, Spain and Australia. I also uploaded Les' test results from FTDNA to MyHeritage and he does not match Mary, Spain or Australia, confirming what I see in DNA Painter. John's daughter is on GEDMatch, but John is not. John's daughter is not in Les' match list on GEDMatch. Does any of this make a difference?

As far as matching Thomas' wife. I am not distinguishing between Thomas' and his wife with their descendants. I know Australia is related to Thomas. I do not yet know of the relationship between Spain and Thomas vs. Thomas' wife. I'll keep this in mind, for sure. At this point, do you think it's important to differentiate between Thomas' and his wife?
This can happen when grandparents take over and raise an "illegitimate - I hate the term we're all legitimate" daughter of a young child.   Then the aunt grows up as a sibling.   Sometimes even the child does not know.   Happened more than once in my tree.
I had posted something else, wrongly, so I hid it. I don't have the names associated with identities intimately, so I get them mixed up. I forgot that Harold is still Les's grandfather. So his Kinzey match makes sense, as does the fact that your father doesn't match that Kinzey man.

Here's a good starting place for Irish records: https://www.irishgenealogy.ie/en/
Also one of the first things you should know: civil registration of marriages didn't happen until 1845 (Catholic was later) and of births/deaths until 1864, and a terrible fire during the Irish revolutionary period destroyed *tons* of records, like almost all old probate records, most of the nineteenth century censuses, and lots of other important stuff. So Irish research gets *very* difficult if you need to go back to people born in the 18th century or earlier.

Thanks for the link and the information about Irish genealogy. It sounds like it's going to be just as challenging as my Jewish side!

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