Imagine that Gary and Harry are these two guys in a hypothetical family, described in English below and in this diagram represented by the green cells at the bottom:

diagram of Gary and Harry's blood lines

As you see, Gary and Harry are related to each other by blood, so one is the other’s something or other. What I want to know here is what that something is. That way Gary could tell someone that “his _______ Harry stopped by the other day”, or vice versa.

In other words, is there a word — or words — that fit these two blanks?

  • Gary is Harry’s ________.
  • Harry is Gary’s ________.

This might be the same something, like with cousins, or it might be different somethings, like uncle and nephew.

Here’s their family tree, which starts with two couples, Andy and Betty on one hand and Charlie and Daisy on the other, in which none of the four is related to any other of the four by blood, only by marriage alone.

  1. Andy and Betty marry and have a son Eddie.
  2. Charlie and Daisy marry and have a daughter Fanny.
  3. Later, Andy divorces Betty and marries Charlie and Daisy’s daughter Fanny, and then Andy and Fanny have a son Gary together.
  4. Also later, Daisy divorces Charlie and marries Andy and Betty’s son Eddie, and then Daisy and Eddie have a son Harry together.

That means that Gary is Andy’s son and Daisy’s grandson, while Harry is Daisy’s son and Andy’s grandson. Gary’s half-brother Eddie is Harry’s father, while Harry’s half-sister Fanny is Gary’s mother.

Given that Andy is Gary’s father and Harry’s grandfather, and Daisy is Harry’s mother and Gary’s grandmother, Gary and Harry are definitely related to each other — but how?

  • Gary is Harry’s ________.
  • Harry is Gary’s ________.

While I realize that not all extended, by-marriage family relationships have a name for them in English that do have a word for them in other cultures, that’s not what I’m talking about here. These are for people who actually share blood with each other, so you would think some combination of cousin or uncle or nephew or grandson would work here.

But what?

Here’s that diagram again in case in helps to see it closer to the English description.

diagram of Gary and Harry's blood lines
This idea and original diagram from F.M. Lancaster’s Genetic and Quantitative Aspects of Genealogy: Types of Collateral Relationships

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    I can't focus long enough to figure this out. I wonder if someone at genealogy.stackexchange.com would have a faster answer? Commented Aug 12, 2018 at 20:23
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    Not really. It helps that there's symmetry involved. (Maybe.) My parent's parent's son would be my uncle. So, if I'm Gary, Harry would be my uncle. On the other hand, if I'm Harry, Gary would be my uncle. Which makes us both each other's uncle. But, transitively, we'd also have to be each other's nephew. It's similar to incestuous relationships where dual labels apply. (Although it's not incestuous in this case.) I could be wrong. That's as far as I can wrap my head around it. Commented Aug 12, 2018 at 20:39
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    @JasonBassford That smells like most of the way towards the right answer to me. For the record, I’m not looking for the time-traveller paradox/chestnut that runs “I’m my own grand-paw”. :)
    – tchrist
    Commented Aug 12, 2018 at 20:40
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    @tchrist, the old novelty song isn't about time travel -- it's actually very close to the situation described. A young man marries an older widowed lady who has a grown daughter; the young man's father (a widower) marries the grown daughter, and both couples have a child.
    – JDM-GBG
    Commented Aug 13, 2018 at 12:49
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    Are the two diagrams the same? Why post it twice?
    – Barmar
    Commented Aug 13, 2018 at 16:58

3 Answers 3


You'd talk about the father's side and mother's side separately. (Credit @JoshRagem's half-uncle / half-nephew idea.)

Consider Gary.

  • Father's side: trace the relationship through Andy. Harry is the son of Gary's half-brother. So Harry is Gary's (half-) nephew on his (Gary's) father's side.

  • Mother's side: trace the relationship through Fanny. Harry is Fanny's half-brother. So Harry is Gary's (half-)uncle on his mother's side.

An uncle is the brother, half-brother, step-brother, or brother-in-law of one's parent, or the husband of one's aunt. - wikipedia

So Harry is Gary's paternal (half-)nephew on his father's side and (half-)uncle on his mother's side.

Correspondingly, Gary is Harry's (half-)nephew on his mother's side and (half-)uncle on his father's side.

  • Although 2 halves normally make a whole, one half can make a whole here all by itself.
    – Lawrence
    Commented Aug 13, 2018 at 2:12
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    Thanks. Looking at it from both sides seems to be the right answer here. Prepending maternal/paternal or appending on the mother’s/father’s side to each of half-uncle and half-nephew makes the most sense to me. That makes them each each other’s half-uncle and half-nephew, irrespectively as it were. Usually only cousins and siblings are reciprocal relationships with the same name both ways; nephews and uncles aren’t — except in this peculiar arrangement with our pair of simultaneous “uncle-nephews”, and then only because it’s accounting those by halves.
    – tchrist
    Commented Aug 13, 2018 at 10:20
  • I’ve added the image credit and link to the page where I got the idea from. The overall site at genetic-genealogy.co.uk is Quite Interesting.
    – tchrist
    Commented Aug 13, 2018 at 10:31
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    @tchrist You're welcome, and thanks for the link. Some of the drawings look like stick-drawings of constellations. When the terminology gets that hairy, it's time to refactor. I like the x-cousin-y-removed scheme for its simplicity. It just needs to be extended a little to cover the missing 2 generations (own generation and the parents' generation).
    – Lawrence
    Commented Aug 13, 2018 at 10:38
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    @Charles It's funny that the Romans seemingly had a sidedness distinction only in the uncle direction, not in the reciprocal nephew direction: those were always nepotes (whence our English word nepotism) either patri- or matrilineally that I can see.
    – tchrist
    Commented Aug 13, 2018 at 22:00

Based on some comments of the question itself, I'm going to pose this as a possible answer.

Purely on the final result of the "family tree" we have the following analysis:

  • Gary's mother is Fanny and Fanny's mother is Daisy. This makes Daisy Gary's grandmother.
  • Daisy's son is Harry.
  • This makes Harry Gary's uncle.

The same relationship can be given if analyzed from Harry's perspective:

  • Harry's father is Eddie and Eddie's father is Andy. This makes Andy Harry's grandfather.
  • Andy's son is Gary.
  • This makes Gary Harry's uncle.

So, Gary is Harry's uncle and Harry is Gary's uncle. This makes them both each other's uncle.

Transitively, this also makes them each other's nephew.

In incestuous relationships, one person can be labelled with two different relationships to somebody. For instance, where a mother and son produce a daughter, the mother is both mother and grandmother to the daughter.

In this question, there is nothing incestuous happening. However, because of the divorces and marriages, it has the same kind of sense.

The divorces and marriages may or may not cause some additional confusion. In my analysis above, I only traced each person's genealogy through a single parent relationship.

I'm not completely certain if this makes them half-uncles (and half-nephews) or not.

It's also possible that there are some additional half- or step- terms that could be used. But my brain holds up a white flag at this point and won't keep going . . .

  • In some countries it is legal to marry one's great grandfather. If this leads to offspring or not is another matter. Commented Aug 13, 2018 at 16:17

Adding on to the above answer:

If I were watching a British tv show, I would absolutely expect them to say “my half-uncle Gary came by today?”...”well he is my half-nephew too”. Bonus word play for 50% uncle 50% nephew

  • Normally you might expect two halves to make a whole...something. But maybe not here. :)
    – tchrist
    Commented Aug 13, 2018 at 1:02
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    Sounds like a perfect excuse to resurrect the archaic "nuncle"! "My nuncle Gary came by... well, he's my uffew, too." Commented Aug 13, 2018 at 3:50
  • @Quuxplusone My thoughts exactly! Commented Aug 13, 2018 at 8:20
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    @Quuxplusone The form you mention, a nuncle, which can still be occasionally heard in colloquial dialectal speech in England, is a variant of an uncle formed by metanalysis that transfers the -n from the article over to the noun. The now very nearly completely obsolete word that could be useful if only we still had it is eam, sometimes spelled eme or even eeme. This originally meant maternal uncle in contrast with a paternal uncle, but that “sidedness” aspect grew blurry over time and so becoming an exact synonym for an existing word was lost.
    – tchrist
    Commented Aug 13, 2018 at 10:39

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