#100: Centennial Edition: Pop Quiz

100.1  Take the Pop Quiz or don’t take it…it’s all the same to me. You could even think of it as a Mom Quiz. And you might find next week’s answers interesting and enlightening…without actually bothering to work out the solutions yourself. I’m fine with that either way.

quiz warmup

100.2  The above is a warm-up, to flex the old gray cells, if any. 4 individuals are denoted by ???…you must supply their relationship to the person designated YOU. Spelled out, the questions are: What is your father’s uncle to you?…What is your father’s 1st cousin to you?…What is your father’s 1st cousin’s son to you?…And what is your father’s 1st cousin’s son to your father?

100.3  …and to answer those 4 questions correctly is to understand our entire kinship system, beyond the father/son, brother/sister, uncle/nephew, grandpa/grandchild basics. Yeah, that’s some “warm-up”…

100.4  Then we have the next 5 kinship diagrams…I need to know how X and Y are related to each other…both in words…like: they are 2nd cousins once removed…and in terms of a fractional Coefficient of Relationship, bearing in mind that parent and child are related by ½…1st cousins are related by 1/8…etc.

quiz 1 quiz 2 quiz 3

100.5  You’ll probably notice that there is a common theme running thru these 5 diagrams…and you’re right, it’s what I call “tag-team” half-siblings. I designed it this way to either simply it…or make it more confusing…take your pick…  😉 😉

100.6  Answers next week…so you have 168 hours…no, you don’t need more time…BEGIN! 

Wicked Ballsysorry

Somebody posted that Kermit thing on my Facebook, and try as I might, I couldn’t stop myself from diagramming it out…Bonus Points if you can name the muppet in the lower right, about to hurl a halibut…

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Copyright © 2012 Mark John Astolfi, All Rights Reserved

 
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#99: 7/8ths of What Again?

chart 346 again

99.1  Last week I left you with a real-world example of “7/8th brothers”…a couple of bulls from a sale last year, and asked how closely they were related. But what’s the big deal about 2 individuals that share 7 of 8 great grandparents? That’s very close to 8 of 8 great grandparents, you see? Practically the same thing…sort of…kind of…like…so how can you go wrong?

99.2  And what’s so wonderful about sharing 8 of 8 great grandparents? Well, it definitely means you’re blood relatives…and at least closer than if you shared fewer great grandparents than that…or none at all…duh. As far as livestock goes…horses, cattle, etc…the sharing of grandparents (quarter fractions) and great grandparents (eighth fractions) predates the modern understanding of genetics by hundreds if not thousands of years. The problem is, what if all your great grandparents are…you should pardon the expression…bum steers? An animal sharing those ancestors would most likely also be a loser.

99.3  So the point was to share ancestors, and as many as possible, with a prize animal…a top performer, a classic specimen. Then presumably your animal would have similar characteristics to the celebrated one…not guaranteed of course, but chances were great, or so the thinking went. Thus the exact Coefficient of Relationship between 2 individuals with the same 8 great grandparents wasn’t the issue…the identity and lineage of those great grandparents was.

99.4  And I say that because sharing 8 great grandparents does not translate into any one specific CR…it can cover a wide range. The most obvious that would come to mind would be full siblings, with a CR of 1/2, as in Chart 347.

chart 347

99.5  Notice that between the siblings’ parents’ generations (2 individuals) and great grandparents’ generation (8 individuals)…there are 4 individuals making up the grandparents’ generation. That’s standard of course for full siblings. But in Chart 348A, there are 5 individuals in the grandparents’ generation…6 in B and C…7 in D…and 8 in E. In all these cases, the 2 “siblings” at the bottom still share 8 great grandparents…but now their CR’s are as follows, converting to 32nds so as to compare with ½ = 16/32…A 11/32…B 10/32…C 6/32…D 5/32…and E 4/32. Case E are quadruple 2nd cousins, the genetic equivalent of 1st cousins…cases C and D are more closely related than 1st cousins at 4/32…and A and B are more closely related than half-siblings at 8/32.

chart 348

99.6  And tho I haven’t illustrated it, there is another case of sharing 8 great grandparents with just 4 individuals in the grandparents’ generation: that of so called “3/4 siblings” (in human terms now)…which are half-way between full and half-siblings, with a CR of 3/8 = 12/32. And as we have seen many, that times consists of half-siblings thru one parent and full 1st cousins thru the other parents…i.e., 2 individuals who share one parent, with the 2 non-shared parents being siblings.

chart 349

99.7  Even so, we haven’t exhausted all the possibilities yet…how about a tag-team configuration like that on the maternal side of Chart 349. And if you find that hard to follow, I’ve broken it down for you in Chart 350…it’s just 2 different men each having a child with each of 2 different women.

chart 350

Now when a/b and c/d have a child, those 2 offspring have the same 4 grandparents, just in 4 different combinations…and there is no interbreeding involved…no one has has a child with someone they are related to. Those 2 offspring are quadruple half-1st cousins with a CR of 1/4, the equivalent of half-siblings…and their offspring get a quarter of that, or 1/16…that’s on the maternal side. On the paternal side they’re half-siblings…for a total CR of 5/16 or 10/32…the same as Chart 348B.

chart 351

99.8  But wait…I’m still not thru! So far we’ve been assuming that the 8 great grandparent slots are filled by 8 different individuals…what if some of those slots get doubled up? After all, in our original bull example of 7 of 8, 2 of the slots were filled by one chart 352individual. With 8 of 8, we would get, for example, Chart 351, with a CR of 9/16 or 18/32…and notice that now there is interbreeding…the  2 individuals in the parents’ generation are 1st cousins, so the bottom 2 individuals are full siblings as well as double 2nd cousins. Chart 352 takes this to its logical extreme, just 2 individuals filling 8 great grandparents slots, with a final CR of 7/8 or 28/36.

99.9  So much for 8 of 8 great grandparents…CR anywhere from 4/36 to 28/36…thats 1/8 to 7/8. And Lord knows that was just a quick overview…maybe there’s a way to finagle CRs even higher or lower than those.

99.10  But I think you can see that taking that down a step, from 8 of 8 shared great grandparents to 7 of 8, there is going to be a similar spread of possible relationships…with a maximum of 9 individuals in the great grandparents’ generation, and, without interbreeding, between 5 and 8 in the parents’ generation…a typical example being Chart 353, which I calculate at a CR of 7/64. (From last time, FF = thru father’s father, FM = thru father’s mother, MF = thru mother’s father, and MM = thru mother’s mother.)

chart 353

99.11  Except now, the idea of some of those 8 great grandparent slots being filled by the same individuals gets a bit dicey…consider Chart 354. Here, all 8 of Green’s great grandparents are also great grandparents of Orange, yet there is one less “double up,” and so Orange ends up having one great grandparent that Green doesn’t. Is this really 7 of 8? Seems like it should be, even tho only one of the 2 related individuals at the bottom has a unshared or “odd” great grandparent, instead of both having one, as in Chart 353. 

chart 354

99.12  At any event, to answer our quiz…we’ll break it down into components. In Chart 355, we see that Bull 70 and Bull 71 are enhanced half-siblings…they have the same father D and mothers who are related, E and F. And the relationship between mothers E and F is itself one of enhanced half-siblings…the mothers’ have the same father A and mothers who are half-siblings, B and C. Now you can “cypher” this in 2 different ways…E and F are half-siblings thru their father…1/4…and half-1st cousins thru their mothers…1/16. That’s a total CR between E and F of 5/16. Their respective offspring will have a quarter of that, or 5/64…added to the 1/4 70 and 71 get as half-siblings thru their father, for a total of 16/64 + 5/64 = 21/64.

chart 355

99.13  The other way to determine the CR of 70 and 71 is thru their maternal grandparents, without the middle step of figuring the CR of their mothers. Thus they are half-1st cousins thru A and half-2nd cousins thru B and C…a CR of 1/16 + 1/64…which again comes out to 5/64…added to 1/4 from D gives 21/64…it checks.

99.14  Were this a family tree of humans, it might well end there. But a quick check of the grandparents generation reveals that 70 and 71 are not only enhanced half-siblings, but super-enhanced half-siblings…that is, they have the same father, mothers who are related to each other, and mothers who are also related to the shared father. We covered this back in G4BB 46….to review:   

halfs

99.15  Unlikely in human kinship? Not really…consider this scenario: A young couple have several children, then the wife dies. Her sister, the children’s aunt, moves in to help take care of them. She eventually marries the widower and they have a child, resulting in enhanced half-siblings…same father, mothers who were sisters. Now consider this same scenario, except the original couple were 1st cousins…the 2nd wife, being the 1st wife’s sister, is also a 1st cousin of the widower father…result: super-enhanced half-siblings.

chart 356

99.16  So thru Z and A, 70 and 71 are double 2nd cousins…do you see how?

70‘s father D and 71‘s mother F are half-1st cousins = 70 and 71 are half-2nd cousins
70‘s mother E and 71‘s father D are half-1st cousins = 70 and 71 are half-2nd cousins

CR of double half-2nd cousins is 1/64 + 1/64 = 2/64…plus 21/64 from Chart 355…grand total CR 23/64….which is just a shade more distant that “3/4 siblings” or 24/64. Done,  done, and done. Next week…100, and just getting started…

Wicked Ballsy…not!!!

granwhat

Ahem…so much for competent journalism. The “niece” turns out to be a misspelled “gran-niece.” Think about it…what if the headline were about a prominent person’s “son”….but it turned out to be their grandson. You’d call that an out-and-out mistake. So it’s OK to “simplify” grand niece to niece but not grandson to son? Pretty lame, if you ask me.

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Copyright © 2012 Mark John Astolfi, All Rights Reserved

#98: Mucking Out the Stalls

Dear G4BB: You couldn’t leave well enough alone, could you? …from Society Slim and his faithful horse, Saddlesore

98.1  Dear Guys: Yup…busted! Enquiring minds, and all that, right? So here’s the thing: I got to thinking about the clumsy way in which Uncle Wiki defined “three-quarter siblings” for horses. They cited references from books, none of which could be found at my local library…altho one author’s name did pop up…M.E. Ensminger…”Doc E.” as he was called…who died in 1998 at age 90. He wrote 22 books on animal husbandry…horses, cows, sheep, fowl, you name it…and they did have a copy of his The Complete Encyclopedia Of Horses, A.S. Barnes & Co., 1977. Well, if that doesn’t qualify as an expert, I can’t image what would. Alongside it on the reference shelf was Summerhays Encyclopaedia for Horsemen, R.S. Summerhays & Stella A. Walker, Fredrick Warner, 1975.

98.2  So…2 prominent experts…books not blogs, real old-fashioned “dead tree” stuff. Can we settle this equine terminology business once and for all? (Spoiler: of course not, but still fun to try!) But first, to standardize my “Tentative System” (TS).

98.3  The letter designations I’d been using for various kinship relationships were assigned pretty much as they came up…”ad hoc”… so I decided to organize them as simply A, full siblings…B, three-quarter siblings…and C, half-siblings.  An X indicates an in blood relationship, which for full means sharing 4 grandparents but not the same 2 parents…and for three-quarter and half means  sharing a common sire, but different dams. i think it’s significant that I couldn’t find on the net a simple explanation, as opposed to examples, of the term “in blood.” Perhaps that’s because it really does mean different things in different contexts…but we’ll see what happens when the experts weigh in.

98.4  Chart 334 reorganizes and re-letters the different cases….shared grandparents are numbered in green.  What I have chosen to call “half-siblings in blood”…CX…are almost universally called by the same sire…the alternate terms sire-side siblings and half-siblings in blood together account for less than a dozen Google hits. Still, to me the symmetry was irresistible: fractional siblings are thru the mare…fractional siblings in blood are thru the sire…this really helps explain what’s going on, I think. Aaaaaaand they’re off!!!

98.5  Full Siblings…Both Ensminger and Summerhays define this as “having the same sire and dam.” Good start! Ensminger lists all of these “closer-than-1st cousin” relationships under the entry for “Brothers or Sisters” which he defines as “having the same parents or one parent in common.” This caught me off guard at first…I tend to think of “brothers” as meaning “full brothers”…not “full or half brothers”…thus “brothers” wouldn’t share just one parent, but his point of view is perfectly acceptable. Just different ways of looking at it…altho he will very soon contradict himself, as we shall see.

98.6  And BTW…Summerhays gives “own sibling” as a synonym for “full sibling.” I have so far purposely refrained from mentioning this term, as again there is  disagreement as to precisely what it means. Some horsy folks say it simply means “full.” Others attach the further meaning of “raised together”…as an “own” daughter raised with its mother, or “own siblings” raised together. The implication is that as much as a horse’s nature may come from its “blood,” many behavioral traits may be learned during its upbringing. So I’ll just mention that, for what it’s worth.

98.7   Half-Siblings…Summerhays says “same dam, different sires.” Ensminger agrees, and points out: “This is one of the most frequently misused terms.”  No kidding! And this was written, what, 35 years ago? It hasn’t gotten any better, has it? He dutifully uses by the same sire to mean “same sire, different dams” and goes on to say: “This distinction is for a definite purpose, for only a few horses can be [half-siblings] to a famous horse, but hundreds can be by the same sire.” That’s the story we’ve been hearing all along.

98.8  Summerhays does not address this “opposite” of half-siblings as Ensminger does, but so far, our experts are conforming pretty much to TS categories A, C, and CX.

98.9   Full Siblings in Blood…AX…which Ensminger calls simply “siblings in blood,” and Summerhays doesn’t address. But what Ensminger says is interesting: “By the same sire out of full sisters…or by full brothers out of the same dam”…that would be cases AX1 and AX2…but then he goes on to add: “or any combination of exactly the same blood.” That certainly sounds like another way of saying “all 4 grandparents are the same”…cases AX3 and AX4. Still, in these latter 2 cases, horses X and Y do not share even one parent…so “brothers in blood” would strictly speaking sometimes be “brothers” (AX1 and AX2) and sometimes not (AX3 and AX4.) Hate to to get picky, but words mean something…at least once upon a time… 😉 😉

98.10  So that’s a small contradiction on Ensminger’s part. Mind you, as important as having the same 4 grandparents appears to be, the concept still pre-dates modern genetic understanding, since “brothers in blood” who are brothers have a CR of 5/16, slightly more than “brothers in blood” who are non-brothers with 1/4 = 4/16.

98.11  Three-Quarter Siblings…Ensminger: “For example, horses having the same dams and whose sires have identical sires but different dams”…he is referencing case B2 only. And I am gritting my teeth…because he gives an example, instead of an explanation. Now strictly speaking, when you say “for example,” I take that to mean there are other examples…that the one you cited isn’t the only one. But is that what he intended? And if so, what are the other examples? Probably B1, since along with B2, horses X and Y are at the very least half-siblings…they have the same dam…altho they are more than that…”enhanced half-siblings” is the term used in human genealogy. But does he mean to also include non-half-sibling (i.e. by the same sire) cases BX1 and BX2? We simply don’t know. Grrrrrrrrr. And he doesn’t break it down any further…no mention of “three-quarter siblings in blood”…so we’re left hanging.

98.12  On the other hand, for “three-quarter siblings”…which he alternately calls “three parts siblings”…Summerhays says: “Same dam, sires who are half-brothers or by the same sire.”  So he is explicitly including both B1 and B2. No mention of the “in blood” versions, BX1 and BX2 so we simply don’t know where they belong. And that’s what our “experts” have to say. Is it any wonder, given the general “dumbing down” of the populace over the past 2 decades, that there appears today to be no consensus.

98.13  But wait for it…there is one final definition, from Ensminger…and dear friends, it’s a doozie! “Seven-eighth siblings: The progeny of a horse and his son produced by the same mare, or similar combinations of lineage.” Recall, many horsey folk refer to “skipping a generation on one side” as three-quarter siblings, in contrast to the “other” definition, that of 3 common grandparents. Presumably, “similar combinations” would encompass “the progeny of a horse and her daughter by the same sire.” Trouble is, yet again, we simply don’t know what exactly he has in mind…

98.14  …and what’s more, in such a case, as you can see in Chart 345, there is no way that 7 of 8 great grandparents are shared by horses X and Y…4 ancestors are shared as great grandparents of both, and 2 other ancestors are shared grandparents of X and great grandparents of Y. That’s a total of 6 shared ancestors…is it possible that the fact that 2 of these ancestors are one generation closer to X than to Y somehow constitutes the equivalent of a “7th great grandparent”? I need a vacation…

98.15  But I know what you’re thinking…before I go on vacation, I ought to at least show you what real seven-eighth siblings look like…and you’re right…in for a penny, in for a pound, as they say.

98.16  This is taken from a catalog of bulls from last year…7 of the 8 great grandparent slots match…the only difference is at the bottom of each pedigree, Miss Lady versus Miss Nadine. And the bull Eaton’s Assert appears twice in each lineage…here’s how it looks in tree form…

98.17  FF = thru father’s father, FM = thru father’s mother, MF = thru mother’s father, MM = thru mother’s mother.  Eaton’s Assert is a great grandfather to both 70 and 71 in 2 different ways (thru cow LT A3 and thru bull LT A), so he counts as 2 of the 7 shared great grandparents…and these seven-eighth brothers are related how? Answer next week…

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Copyright © 2012 Mark John Astolfi, All Rights Reserved

#97: You Could Lose Your Mind!

Dear G4BB:  Thanksgiving has come and gone, and once again at our family gathering, the traditional arguments raged on…including the one about whether it’s really possible to have “identical cousins” like Patty and Cathy on “The Patty Duke Show.” Can you settle this, so I can be on the winning side for sure this Christmas?  …from Lambsie, in Pie City


97.1 
Dear Lambsie: Be happy to…and BTW, the tomato is a vegetable, not a fruit, got that? But listen…did you take a Biology class in high school? Hey, there’s my old teacher…she was double-jointed and had a habit of leaning on her desk with her arms bending at all the wrong angles. Anyway, she taught us about phenotypes and genotypes…sound familiar? A phenotype consists of all the physically observable characteristics or traits of an organism. A genotype is the genetic make-up that makes the phenotype possible.

97.2  From the point of view of phenotype, is it possible for 2 people, not identical twins, to still be so similar in appearance that they could be mistaken for identical twins? Absolutely…and I’m sure we’ve all seen examples of that at one time or another. I once worked with a women whose teenage sons, separated in age by a couple of years, were to me indistinguishable. Then you have the Olsen girls, Mary-Kate and Ashley…the family says they’re fraternal twins, but they resemble each other to the point where they were both cast as Michelle Tanner on  “Full House” at age 9 months…such a shared role is usually filled by identicals. And in researching this topic, I came across a blogger who remembers 2 unrelated boys from high school who were able to convincingly play identical twins in a school play.

97.3   So between siblings on the one hand, and completely unrelated individuals on the other, it’s certainly possible for 1st cousins to look identical. On the show, Patty’s father Martin Lane and Cathy’s father Kenneth Lane were identical twins. For the record, in the unaired pilot, it was their mothers who were identical…this pilot was never broadcast because a different actor, Mark Miller, played Martin. On the show, it was William Schallert, and he also played his twin brother in several episodes, with a mustache. He even once played Martin impersonating Kenneth.

97.4  And in a second season episode (the show ran for 3 seasons), they took it one step further as Duke played yet a 3rd cousin, Betsy, from Atlanta, with a Southern accent of course. And just for the heck of it, here’s a shout-out to the “4th cousin”…then teen actress Rita McLaughlin…she had been one of the kiddie helpers on “Watch Mr. Wizard,” and stood in for Patty Duke when one of the cousins was seen from the back. Under her married name of Rita Walker, she went on to a career in soaps on “The Secret Storm” and “As the World Turns.”

97.5  But I guess the producers of the show thought identical twin fathers was enough to justify the concept…identical mothers as well would have been even better. With identicals on both sides, the resulting girls would genealogically be double 1st cousins, who are normally are as closely related as half-siblings….but genetically they’d be as close as full siblings. Even so, the way they did it, with identical fathers and unrelated mothers, Patty and Cathy are as closely related as half-siblings…since genetically, their fathers can be considered the same person. So in the sense of appearance alone, “identical [1st] cousins” is a plausible idea…very unusual, but certainly possible in real life. Now in terms of genotype or DNA, it’s a different story altogether.

97.6   Since their mothers are unrelated, Patty and Cathy cannot have identical an genetic makeup, as would be the case with identical twins. Identical twins start at conception as one single fertilized egg…with one single set of genes. The egg then splits into 2, and both halves develop into separate individuals. These 2 identical twins have identical genes because there’s no way that they couldn’t have…the only source of their DNA was that one single fertilized egg and its genetic content. There is simply nowhere else “non-identical” genes could have come from.

97.7  Now to examine this a little further, the reason full siblings are different, both in appearance and in genes, is twofold. First of all…of the approximately 20,000 genes we have, we actually have a pair of each…one from each parent….for a total of 40,000. And to take the father as an example…of the paternal set of 20,000 genes that 2 brothers get, 10,000 will be the same, and 10,000 will be different…that’s because when the sperm cell that formed each brother was produced, its 20,000 genes were a random mix, half from the father’s father, and half from the father’s mother…because the father himself has 2 sets of 20,000 to start with. This “shuffling” of genes is the whole point behind sexual reproduction…each time the father has a child, he gives it a different combination of his genes.

97.8  When I said 10,000 match, 10,000 don’t, it’s never that exact…it’s always more or less, but it’s close, due to random probability. Could all 20,000 match? Well, imagine you and a friend flip coins 20,000 times and every time what you get a match, heads or tails. Ridiculously unlikely, but not absolutely impossible. And since Patty and Cathy’s fathers’ have the same genes…both pairs, all 40,000…let’s assume both girls get exactly the same 20,000 from their fathers. Huge assumption, I know, but play along…

97.9   Now the second way genes control what an individual will be is by the process of dominance. Remember, you have 2 complete sets of genes, one from each parent. So which genes will make you, you? Well, of every pair, one will be expressed, called the dominant gene…and one will be repressed, called recessive gene. Again, it will normally be 50/50, father’s genes versus mother’s genes. But it is not absolutely impossible that all 20,000 of the Lane genes could be dominant…so that effectively Patty and Cathy’s genetic makeup could functioning as if  they were truly identical twins. Just imagine you and your friend flipped coins 20,000 times and got identical results…and did that twice!…once to get identical genes from the fathers, and again so that only the fathers’ genes are expressed, not the mothers’.  That’s how likely it is…which is to say, not very…but that should keep the Yuletide argument going for a while, huh? 😉 😉

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97.10  Couple more from the wiseGeek “Cousins” page…and first-up sounds pretty confident…and confidence is a good thing, generally. In this case, they happen to be wrong, but I’m here…no harm done!

97.11  The trouble is, you reckon cousins from the CLOSEST common ancestor, not from ANY common ancestor. As shown in Chart 343, YOU and your cousin are indeed half-4th cousins…you have a 3G grandfather in common, but your 2G grandfathers are half-brothers, not full brothers, since they have different mothers…and thus you have different 3G grandmothers. All that you got right. But that’s as far as it goes…certainly, your 3G grandfather’s parents are 4G grandparents to both you and your cousin…but they are not your CLOSEST common ancestor…we’ve already established that your 3G grandfather is.

97.12  Using your line of reasoning, that cousins can be figured from ANY common ancestor…2 full siblings, with the same mother and father, would also be 1st cousins, since they have grandparents in common. They would also be 2nd cousins, with great grandparents in common, and 3rd, 4th, 5th cousins, on up the tree. That obviously isn’t right. Again, it’s the CLOSEST common ancestor that determines it…in the case of full siblings, that would be their parents, period…it stops right there.

97.13  And this next one is not a question but a declaration…it needs no response, except to say: whatever floats your boats, twin cousins. Funny how that ties in with Patty and Cathy…but also notice that you are “irregular double cousins,” different on each side…full 1st cousins since your mothers are sisters, but half-1st cousins since your fathers are only  half-brothers. Double 1st-cousins…that is, the same on both sides…have a CR of 1/4 = 4/16, equivalent to half-siblings. Yours is 3/16, just a bit less. But that’s pretty cool you 2 cousins and your dad being born on the same day. Do you look anything alike, I wonder? Next week…gee whiz, who forgot to close the barn door??? See yez then.

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Copyright © 2012 Mark John Astolfi, All Rights Reserved

#96: …Rounding the Clubhouse Turn

96.1  So here’s what happened…I was trolling the net researching the concept of “three- quarter siblings” when I stumbled across its use in the equine world. Seems among horsey people, it’s a common term, due to the fact that horses are neither monogamous nor bound by any inbreeding taboo. Which means what exactly? Which means that while half-siblings and “enhanced” half-siblings (where the unshared parents are themselves related) are relatively rare among humans, they are the rule among horses. Another way to put that…between a Coefficient of Relationship of ½ for siblings and 1/8 for 1st cousins, there are many more fractional gradations routinely produced in the horse world.

96.2  And reviewing from last week, one of the more striking conventions is that half-siblings must share the same mother or dam. By tradition, horses with the same father or sire, but different mothers, are not called half-siblings as they would be in the human world. They are simply called by the same sire. Based purely on biology, the fact that a horse can have a 1000 half-siblings thru its sire, but only a dozen or so thru its dam, supposedly accounts for this asymmetrical way of looking at it. A few scurrilous reformers want to change that, but the hobby resists. One interesting compromise…yet to catch on, but definitely out there…is to call half-siblings thru a sire sire-side siblings. This terminology is intended to suggest that while such “siblings” are not full-fledged half-siblings, they’re siblings of some sort nonetheless.

96.3  Chart 340 collects some typical kinship arrangements between horses X and Y…because of the maternal half-sibling rule, sharing a mother as opposed to a father makes it a difference case, as does the fathers and/or mothers sharing the same fathers or mothers.

96.4  What I did next was to find what looked like a reasonable set of definitions…then compared them to Uncle Wiki and found discrepancies. I located 4 more sources, pretty much in the order that Google gave them to me. Most hits were sites that were using the terms, not defining them. And some sets of definitions were duplications, taken directly from Wikipedia, word for word, as will happen. Chart 339 summarizes the jumble of conflicting meanings. Mind you, I was an outsider looking in, justing wanting to see how it was done…I hardly could have expected such a lack of consensus.

96.5  And just for the fun of it, Chart 341 replaces the lettered examples with their CR…and as you can see, these terms date back to before the genetics of horse breeding was understood in the modern mathematical sense.

96.6   So to what do we attribute this confusing jumble? Poor communication skills? I’m sure that’s part of it. Maybe in some cases, if you were to take a definition and say: OK, here’s a relationship that isn’t included in the definition the way you stated it, did you want it to be? They might say: Yes, I did…I guess I didn’t state it as precisely as I should have. In other words, what they said wasn’t exactly or completely what they meant. But you must remember that such terms as siblings in blood and three-quarter siblings are routinely used in horsey talk, and the assumption must be that the reader or listener understands what’s being described, nez pah? Otherwise, what’s the point?

96.7  And actually, the deeper point is this: Most of the definitions I found were along the lines of “sires are this, dams are that, etc. etc.” Is there something more fundamental behind that way of putting it, some underlying principle that isn’t being squarely elucidated? I think there is…and it comes from what I called Source 4

96.8  Siblings in blood have the same 4 grandparents…aha, now we’re getting somewhere…this is what I meant by an underlying principle. This definition applies to cases A and D…one parent the same, other parents siblings…and also to case I…both parents are siblings to the other parents. In all 3 cases, X and Y share 4 grandparents. Now if they shared 4 grandparents because they had the same father and mother, they’d be just siblings…but because there are more than 2 “middlemen” (more than one father and one mother) between them and the “blood” of their grandparents, they are siblings in blood.

96.9   Since we’ve introduced the concept of shared grandparents, we might then make the leap to this: three-quarter siblings share 3 out of 4 grandparents. Positively tantalizing, isn’t it? Could it be just that simple? Well, I believe that from a certain point of view, it is…I have found references to three-eighths, five-eighths, and seven-eighths siblings, referring to shared great grandparents…sometimes in the same breath as three-quarter siblings. So it’s clear that this is what some horsey folk are driving at when they use these terms.

96.10  Doing it this way, B, C, E, and F…where one parent is shared, and the other parents are either half-siblings or sire-side siblings…and cases G and H…where there’s a skipping of a generation on one side…could be lumped together. As in Chart 339 all these cases are some sort of three-quarter siblings, at least according to somebody.  Yes, I know…in cases G and H, X and Y don’t actually share 3 grandparents…I’ve marked them in Chart 342they would if X’s sire were his grandsire…but perhaps being his sire is even better than being his grandsire, in the sense of being more closely related…??? And yes, if we were doing it strictly genetically, then A and D would be grouped together with G and H…lo and behold, that’s how Source 5 alone does it.

96.11  Again, this terminology pre-dates modern genetics, so maybe it will change sometime in the future. But let’s take a stab at how it’s done today…

96.12  We’ll call this the Tentative System (TS)…and granted, it sure makes logical sense…altho that might not be enough, right? BTW, we haven’t yet seen the term half-siblings in blood…which would presumably be still another way of saying by the same sire or sire-side siblings. I Googled it, and got 3…yes 3!…hits. But one was satisfyingly to the point…

96.13  The colts in question, Bertie and Elmo, have the same sire, out of different dams…they are not half-siblings, since they don’t have the same dam…but the way this horsey person looks at it, they are a kind of half-siblings…half-siblings in blood. And Google found me 2 other people in the world who have the temerity to put it that way.

96.14  But is it possible that TS is in fact the way horsey people think, and that as a breed (sorry!!) they simply lack the ability to communicate it as succinctly as this? Good question…let’s take a closer look at exactly what Uncle Wiki says about three-quarter siblings…

96.15  Even before we get to comparisons with TS, there’s a lot here that doesn’t add up. “(Maternal) half-brothers” doesn’t make sense…there is no other kind of half-brothers…”(paternal) half-brothers” don’t exist. And why does the third definition, that of three-quarter genetic siblings, say “put simply, horses that share three grandparents”? That applies to the other 2 definitions as well. Was the “put simply” part meant to apply to all 3 definitions? Well, there you have your poor communication skills…there’s really no way to tell what the heck they intended.

96.16  But now look at B, C, E, and F…in B, horses X and Y are half-siblings (same dam) and their sires are half-siblings…in C, X and Y are half-siblings (same dam) and their sires are sire-side siblings or by the same sire.  In both cases, they are half-siblings and share 3 grandparents, so TS groups them together as three-quarter siblings. B qualifies with Uncle Wiki, but not C…perhaps because there are 2 half-sibling relationships with B…dams and paternal granddams…but only one with C?

96.17  Similarly, in E…X and Y are sire-side siblings, and their dams are half-siblings…where F has sire-side siblings whose dams are also sire-side siblings…no half-siblings involved at all in F. So for Uncle Wiki, E gets the nod as three-quarter siblings in blood, but not F. Still, they think F should be something, so we get three-quarter genetic siblings. For the record, I got a minuscule number of Google hits on that non-traditional terminology…”three-quarter genetic brothers” 123 hits…”three-quarter genetic sisters” 1 hit…”three-quarter genetic siblings” 0 hits…”three-quarter genetic relatives” 19 hits.

96.18   But more importantly, while F, involving NO half-siblings at all, gets a definition…C, which includes half-siblings at least thru the mother’s generation does not…and arguably C is more significant than even E, which includes half-siblings only thru the grandmother’s generation…and E does get a definition. See what I mean? Something just doesn’t jibe with Uncle Wiki…and the sources they site are books, not websites, so I haven’t been able to check them. Looks like another case of taking Uncle Wiki with a good lick from the salt block, sez me…

96.19  And of course, Uncle Wiki includes cases G and H in its definitions, where a generation is skipped on one side…horse X’s parent is Y’s grandparent. I didn’t include them in TS simply because they don’t follow the shared grandparents scheme…altho as we’ve seen, X and Y do share 3 ancestors…2 as grandparents…and 1 as parent of one and grandparent of the other…presumably this is even “better” than sharing 3 grandparents. Except that genetically…thus genealogically…”better” means “different,” and precision demands you distinguish between these cases. It looks like horsey folk have a dual system going on with three-quarter siblings…it could mean 3 shared grandparents, or it could mean parents who are father/son or mother/daughter…skipping a generation on one side. Two different things, called the same thing…and it appears this ambiguity is something they’re willing to live with.

96.20  But to take this race down the home stretch and to the wire…I found a very interesting discussion on the net about just these issues…yes, people in the hobby are aware of them…and I have drawn from it 4 comments which I think will be enlightening…

96.20  Comment Aon three-quarter siblings, agrees with Source 6 and TS…on three-quarter siblings in blood, agrees with Uncle Wiki…and almost with TS…I say E and F, they say E and H…did they mean to exclude C and G? Dunno…

96.21  Comment BWow! Hold the presses! Magic Millions and Inglis are big-time horse-traders in Australia, and the suggestion here is that what one of them would correctly call half-siblings, the other will bump up to three-quarter siblings, “to make pedigrees look much better.” When I said “poor communication skills,” I was trying to give the benefit of a doubt…but here, they’re talking “fraud”…gotta love it!

96.22  Comment C…Kind of agrees and disagrees…kinda. Notice “open to interpretation” and “that’s how it used to be.”

96.23  And finally Comment D…which in the first sentence re-states the traditional idea that siblings of both the half and three-quarter variety MUST have the same dam…and in the second, suggests the more modern, genetically-based approach. And there it is in a nutshell…old or new?…”blood” or genes?

96.24  Bottom line: there is a more-or-less standard way to describe equine kinship, and it seems as if TS gets very close to that. But some people get sloppy…or are just plain ignorant…or aim to misrepresent…or are reformers with an axe to grind. And as with human kinship, sometimes horsey folk simply learn slightly different classifications.  At least that’s what this outsider sees when he’s looking in. Welcome to life! Mail-bag next week…and does a hot dog make YOU lose control? … 😉 😉

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