Oh, Brother! A Look at Full Brothers in Pedigrees

re: Oh, Brother! A Look at Full Brothers in Pedigrees

Alan Porter — Mon, 26 May 2014 01:12:29 GMT

I would guess a lot of reasons to do with the type of horse, the degree to which the inherited similar variants for performance and aptitude, and where and when they stood.

With Sadler's Wells and Fairy King, I would have had the impression that Fairy King would generally be inclined to get a less staying type.

Similarly, Diesis was certainly more precocious than Kris, and he would have tended to receive rather different mares standing in the U.S., where Kris stood in England.

With Devil's Bag, I would suspect that the Mr. Prospector mares he covered were 1) sired when Mr. Prospector was younger, and 2) where probably much nearer peak producing years when they visited Devil's Bag.

Graustark and His Majesty were somewhat different types, but did at least stand at the same place at the same time, and cover a lot of the same mares.

re: Oh, Brother! A Look at Full Brothers in Pedigrees

sceptre — Sun, 25 May 2014 22:28:58 GMT

There is no (scholarly) genetic rationale to suggest that the dam has more "influence" on physique or aptitude. Don't be fooled by anecdotes; one can easily offer them to the contrary. Yes, for example, Crimson Saint's aptitude probably did dominate in her offspring, as this is quite possible genetically- just as Crafty Prospector (the stallion) tended to dominate, aptitude-wise, in his offspring. One can get all variations on the theme. for Some stallions, and some dams tend to dominate re-outward appearance. This too is genetically possible. But, all examples such as these are the rarities; a basic blending is far more common as we're dealing with a large number of alleles- unlike when one parent is a BB (homozygous brown) for eye color. Here, all offspring (regardless of whether the other parent was blue or brown eyed) would possess brown eyes.

re: Oh, Brother! A Look at Full Brothers in Pedigrees

Pedigree Ann — Sat, 24 May 2014 11:22:34 GMT

"Is the reason why say Sadler's Wells is who he is because he got more than the average 50% of the variants/haplotypes found in Northern Dancer and Tate Gallery is who he is because he got less than 50% and more of Fairy Bridge?"

The dam having more influence on the type of physique and aptitude of the offspring is always a possibility. Nijinsky surely seemed have gotten more of his mum - taller and rangier than dad, and quite stoutly bred as well; she won the 10f Queen's Plate over colts.

Terlingua always seemed more like her mum, the closet Quarter Horse Crimson Saint, than like Secretariat. And to me, her son Storm Cat seems to throw to one or the other parent - to Storm Bird, who sired more than one classic-type horse, or to 7f specialist Terlingua. Storm Cat in the pedigree may not mean the same thing in every context.

re: Oh, Brother! A Look at Full Brothers in Pedigrees

sceptre — Fri, 23 May 2014 22:03:02 GMT

Byron,

Re-your last post: Of course that's true-in that it's very hard to make generalizations (so I assume your method here was Socratic?). The genetic variables are enormous, but a sophisticated attempt/study of probabilities might prove productive.

re: Oh, Brother! A Look at Full Brothers in Pedigrees

sceptre — Fri, 23 May 2014 21:27:29 GMT

Well, Byron, on to your last question-about Sadler's Wells and Tate Gallery, etc...Firstly let's clear something up for some of your readers. Both Sadler's Wells and Tate Gallery have 50% Northern Dancer genes and 50% Fairy Bridge genes-no need to say "on average" here. And, within your context when you say "variants/haplotypes" what I assume is meant here is + variants/haplotypes. So, that's a bit of "house cleaning" to help others better understand what you're trying to convey. Byron is not implying that, for example, one son received MORE Northern Dancer genes than the other. But he is speculating that Sadler's Wells may have received more of Northern Dancer's POSITVE allelic variants/and haplotypes than did Tate Gallery. He is also speculating that Sadler's Wells may have received more of Northern Dancer's + dominant genes whereas Tate Gallery may have received more of Fairy Bridge's dominant genes. Anyway Byron, if that's not what you meant then we are in immediate disagreement re-some basic genetics...Now when you say "SIRE sons of elite stallions..." this generally connotes that those sons were very capable racehorses, and seems to suggest that their racing ability was more likely due to having received a higher proportion of their sire's +variants (which, on average, would tend to be more abundant than would their dam's). This type of conjecture is very similar to my last post about your Galileo/Danehill/Buckpasser issue, and also my last post to Alan (in previous blog). I think it's open to debate worth pondering and probably can be resolved with a lot of mathematical analysis.

re: Oh, Brother! A Look at Full Brothers in Pedigrees

Byron Rogers — Fri, 23 May 2014 21:00:37 GMT

Sceptre,

I tend to agree with Ann in that it is very hard (but not impossible) to make generalizations about who has inherited what in terms of variants/haplotypes (most of the reason why the X-Factor is complete bunk). It is of course muddied by the fact that there are a lot of different ways to be a good racehorse and you only have to beat who turns up on the day.

re: Oh, Brother! A Look at Full Brothers in Pedigrees

sceptre — Fri, 23 May 2014 20:30:42 GMT

Boy Byron, you have a knack for unwittingly (meant in a + sense) re-opening a topic of the very last TrueNicks blog (Alan's piece). This is at least the second recent time this has happened-and on both occasions it went without real resolution. I mention this in reference to your aside (stimulus for this piece) about the Galileo/Danehill/Buckpasser etc. query. Galileo's Buckpasser and Danehill's Buckpasser come through Hopespringseternal and Spring Adieu respectively. The former was unraced and the latter was a minor winner (I liked her, though, and once tried to purchase her privately (for myself) prior to the advent of Danehill)). But anyway, I wouldn't consider them to be top sources of Buckpasser. Anything's possible, but all else equal, I'd consider it less likely that the "Buckpasser connection" is that causative in the apparent success of that "nick".

re: Oh, Brother! A Look at Full Brothers in Pedigrees

sceptre — Fri, 23 May 2014 20:05:13 GMT

Keep in mind that while full siblings may "look" differently should not imply that their total genomes are less similar than full siblings that "look" more the same.

re: Oh, Brother! A Look at Full Brothers in Pedigrees

Byron Rogers — Fri, 23 May 2014 19:43:06 GMT

Ann/Sceptre,

You both came with the same answer which I expected. I wasn't so much asking for "heavy lifting" to be done, rather putting the questions out there for discussion. It was sparked by a conversation with another pedigree analyst who suggested that Buckpasser was the 'cause' of the success of Galileo with Danehill mares to which I responded, why hasn't he worked with Eagle Eyed mares, or Black Sam Bellamy with Danehill mares?

I've updated the post to your question Sceptre - interesting that you both used His Majesty/Graustark. That duo must have been more your generation :)

So then the question becomes, if a horse on average has 50% of its own sires genes and 50% of its dam's genes. Is the reason why say Sadler's Wells is who he is because he got more than the average 50% of the variants/haplotypes found in Northern Dancer and Tate Gallery is who he is because he got less than 50% and more of Fairy Bridge?

Do the sire sons of an elite stallion share more in common with their sire in terms of percentage inherited from them?

re: Oh, Brother! A Look at Full Brothers in Pedigrees

Pedigree Ann — Fri, 23 May 2014 19:04:15 GMT

"It would be interesting to hear some theories on why that occurs." -

Well, one could start from the fact that on average, full siblings have only 50% of their genetic material in common . And that's an average - it could be more or it could be less. A group of dominant or semi-dominant alleles that Sadler's Wells got from his dad, may not be expressed in Fairy King - he got the recessive lot. Or vice versa. They might not have received the same X-chromosome from mum - she has two on offer, after all.

Full siblings can be quite similar, or they can look like my brothers and I look in a group photo - are these 4 people really related? Graustark was big, striking chestnut, His Majesty was a smaller standard-issue bay. Working only from paper pedigrees doesn't tell you everything.

re: Oh, Brother! A Look at Full Brothers in Pedigrees

sceptre — Fri, 23 May 2014 16:21:42 GMT

Hi Byron

Dare I say, you're asking us to carry much of the load.

For starters, while the offspring of any given stallion, and that stallion's full-sibling should, ON AVERAGE, possess 50% of that stallion's genes, any (above) offspring will ALWAYS possess exactly 50% of those genes while any individual full sibling's genome possession can (theoretically) vary between 0-100%. There are, obviously, many other genetic and "commercial" variables involved in why some full siblings tend to mirror the other at stud, while others don't...If you would, supply us the stats for Graustark and His Majesty with, say the Tom Fool-line. It's my perception that it worked well for both-I'm relatively sure of this-, but I doubt your stats will confirm. Should they not, this may be another fertile topic for discussion.