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 342…they 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 A…on 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 B…Wow! 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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