Understanding Pedigrees

How to Look at
Sport Horse Pedigrees

[The Tetrarch, a typesetting Thoroughbred whose traditional pedigree has been found to be in error. public domain image]

Much of the information formally on this page will now be found on the Pedigree Generation Position page. I felt it made more sense to give you the basic points needed in understanding pedigrees, the format they come in--basic pedigree structure, what the positions mean, definitions that are used throughout the site and in pedigree analysis, genetic facts that apply to our evaluations and Tesio Methods here on this page. The information printed below I have previously published in my last two books as a primer in the appendices. For detailed instruction on these principles see my first book (see book info). All the pages on this website and in the books are of course under copyright, and I post them here for your personal use and instruction. You are welcome to print out whatever you want or need for your own information, but you are not allowed to re-publish my work in books, magazines, e-books, blogs and websites without my permission (copyright).

Understanding Pedigrees (adapted from Appendix B of Legacy of Lexington and Standardbred Sport Horses).

* Importance of Accuracy

The pedigree is the map of the genetics. It becomes a powerful tool for our use in understanding dominance and in the designing of our breedings if it is accurate, and if  we know how to read it (interpret).

Accuracy in pedigrees, as you will learn through reading the books is not guaranteed. Over the years many mistakes were made in building out lineages, plus illustrious ancestors were sometimes invented by owners and breeders to advance their horses in sales or to qualify for stud book requirements or to elevate their stud fees. Therefore, we must do our best to verify our pedigrees. It is only a powerful tool when it is correct--a road map of the genetics--but all that positive potential is lost if the lineage is false.

An interesting example of a pedigree that proved false is The Tetrarch, seen at article start, whose traditional lineage really didn't reflect his tremendous genetic footprint. He was a brilliant sprinter and undefeated as a two-year old, but was retired with poor front legs. He was also had a low libido and was not very fertile--I think you would agree he does not appear to be a very good candidate for establishing a powerful sport bloodline, especially for jumping--but that is indeed his legacy, and he is consistently found in great show jumpers, usually in multiples. His traditional pedigree didn't really explain his genetic strength, and it turns out there is a reason for that.

In 2012 Dr. Bower published her findings that the famous stallion Bend Or was a fraud. It turned out Bend Or was really a horse named Tadcaster, who was by the same sire Doncaster but out of a different mare: Clemence. When I applied this new discovery to my database, replacing Bend Or with Tadcaster, all of sudden many mysteries were solved, the most dramatic example was in The Tetrarch. With the corrected pedigree The Tetrarch was shown to be extremely potent as he is 3x3 to the full siblings Tadcaster/Clementina. Now we had a pedigree structure that explained this powerful bloodline. And more than that it revealed the unheralded mare Clemence was possibly one of the greatest sport broodmares of all time--because she is not just the dam of Tadcaster, but of The Mersey, the dam of Carbine. Carbine is an Australian-bred super sire, and among others he is the sire of Spearmint, another unlikely but strong sport bloodline. Spearmint was a constant in show jumpers as well and he too had poor front legs. Tadcaster was also the sire of  a legendary broodmare Fairy Gold, who is the dam of Fair Play, a strong stamina line in the USA and a lasting jumper line. On three continents, three sport dynasties all with the mare Clemence at their base---a mare no one ever wrote about, and there she is, a fountainhead of stamina and jumping talent--overlooked until now because of a pedigree fraud committed one-hundred-thirty years ago.

The most comprehensive way to evaluate the pedigree is found in what is called Tesio Methods, which is a presentation of pedigree patterns that have proved to be statistically more beneficial for building potency; we can use them first as a means of judging the potency of a horse, which bloodlines it is dominant in and how strong that potency is especially when we combine it with the latest scientific findings. And as breeders we can apply that knowledge in finding a truly suitable mate for our horse, by being able then to judge what genetic strengths a particular mating will provide. A step by step instruction on how to use these methods is presented in North American Sport Horse Breeder in Section II, so I will not go into great detail here, but will provide a simple outline on its main points for your use here.

* Definitions:

Inbreeding: common ancestors three generations or closer (1x3, 2x2, 3x6 etc.)

Linebreeding: common ancestors in the fourth through tenth generation (5x4, 6x6, 5x9 etc.)

Outcrossing: no common ancestors in six generations

Crossbreeding: sire and dam from different breeds (Saddlebred/Holstein, Thoroughbred/Morgan, Standardbred/Dutch etc.)

Standard Pattern: a combination of ancestors that are seen more often than not in a breed--such as Mansfield and Ulysses in the Morgan, Ali and Falb  in the Holstein, Nasrullah/Mahmoud/Royal Charger in the Thoroughbred, Guy Wilkes and William L in the Standardbred.

Nick: a combination of ancestors that has proven to produce exceptional offspring, examples--Fair Play/Rock Sand, Lexington RH/Glencoe in the Thoroughbred and Adios/Tar Heel in the Standardbred.

Engine Room: title give for the important pedigree position of the 4th through 6th generation, which scholars have identified as the key place for refocusing background strength (balanced linebreeding).

Filly Factor: a combination of offspring patterns that have proven to produce the best fillies and mares---these can either be sons and daughters of a mare and/or daughters of a key sire (no sons). All breeding stock, both stallions and mares benefit for a strong filly factor or two as well as strong colt factors.

Colt Factors: these can be both sons and daughters of a key sire, and/or sons of a key mare (no daughters), and they are a notable factor in performance. While the best performance colts and geldings can get by with just colt factors , the best performance mares need a filly factor as well.

Sex-linked material: large heart gene is an example, also respiratory efficiency and energy conversion are some of the traits that travel on the x chromosome--therefore on the dam-lines. Sex-linked traits travel from a sire to his daughters only and from a mare to both her sons and daughters.

Mitochondrial DNA (mtDNA)--the DNA material supplied only by the dam which has been determined to contain respiratory efficiency level and energy conversion matter, plus some genetic material related to heart function and fertility. Because energy conversion is so vital for the sport performer, the quality of the mtDNA is an important factor in successful sport horses and broodmares. The geneticist Ann Bowling referred to it as the 'metabolic power station'. 

phenotype: the appearance and performance of a horse, it does not necessarily represent the whole genetic package carried by the horse.

genotype: the full genetic fabric of the horse.

Critical Mass: term given to the point when the genetic concentration of superior traits becomes so great that first class horses are regularly produced. A guarantee of critical mass is to have a large buildup of an ancestor in the background of the lineage ( 7 to 14 generations) and then to have it strongly refocused in the engine room area (4-6 generations)--statistically proven by Harper. Creating critical mass in our designs of a desired ancestor is to set its type into our foals--a very important goal for sport success.

* Helpful Genetic Facts:

Dr. Bowing states that genes travel intact down through the generations (unless a mutation occurs); that is why if you build up a background ancestor (and its close relatives) eventually you will see the type strongly in the foals, even if it is far back in the lineage.

Phenotype usually represents a fraction of DNA material found in a horse, that is why there can be a sire or mare with no sport ability or racing record, or even one with poor conformation that is able to produce offspring that far exceed it in quality, or on the other hand, a stallion who is a great performer may not be able to reproduce his talent or type in his offspring because he is not potent in the traits he himself displays..

For a talent to be manifest in the horse it must first of all be present in the pedigree, however for the horse to be able to pass that talent on consistently it must not just be present, but be so in potency. If a horse demonstrates a level of talent or potency that his pedigree does not reflect, then that is a clue that the pedigree is in error. Two high profile examples of that are The Tetrarch (top jump transmitter--see above) and Figure RH (foundation sire of the Morgan breed)--both had errors in their traditional pedigrees, and their genetic reach was far greater than reflected in their traditional lineages.

Inbreeding concentrates whatever is in the pedigree--good as well as bad, and inbreeding can cause recessive genes to appear that were hidden. Inbreeding of itself does not create negative traits--it just makes those present be more prevalent in the foal. Conversely it does not create positive factors either, it just makes them more certain in the foal as well. Inbreeding is the quickest way to set 'type'.

Genes travel in clusters (Bowling), so targeting a carrier of a specific trait for duplication can bring down other factors, if the target ancestor was a superior horse than this is a very positive thing. Creating full sibling configurations increases this advantage even more, which is why it is one of the strongest designs in pedigree potency.

Performance is the ultimate proof of our breeding designs, however proficiency at a sport at any level has been statistically shown (Losey et al) a strong indicator of superior genotype, and conversely poor performance in sport at any level is an indicator of mediocre genotype.

* Pedigree Structure:

In order to read a pedigree we need to understand its structure. We will use the pedigree of the great stallion Hamburg (he amazing genetic traits are discussed in Speed Gene page) to discuss pedigree design--so print it out or put on parallel screen for reference.

His sire is Hanover--the sire is always in this position (top of pedigree). His dam is Lady Reel--the dam is always in this position (bottom of pedigree).Therefore the sire on top/dam on bottom. When you read about the  tail-male line what they are speaking of is seen here in Hanover/Virgil RH and beyond. Just being on the male side of the pedigree is not included in tail-male, so Bonnie Scotland, the sire of the sire's dam is not included in the tail-male line. The 'RH' breed designation appears on all American racehorses up to 1818 when the trotter became a breed of its own (performance standard set) and those racers were then American Trotters (AT), all galloping racers were still Running Horses (unless of full English TB blood) until 1868 which was the year the American TB was established, nor did the Quarter Horse exist as a breed until then and our pacing Running Horse remained a breed until its last remnants were absorbed into its descendant breeds and then it quietly went into extinction--all pacing Running Horses were absorbed into the Standard Register in 1891, but there is evidence there were still pockets of Running Horse still around until 1925.

When you read about tale-female lines, this would be represented here as Lady Reel/Mannie Gray/Lizzie G RH and so on--it does not include Aerolite RH, the dam of the first dam's sire.

Sex-linked characteristics travel only on the x-chromosome pathways. In Hamburg, because he is a stallion, this would be demonstrated as the tail-female line outlined above, plus from Aerolite RH to Fellowcraft to Lady Reel--so Aerolite RH contributes one of the x-chromosomes. This is because each mare has two x-chromosomes, and so she would give one of her two to Hamburg. At this stage of scientific study there is not a way to determine which of the two x-chromosomes he would get. Although this may be one of those mysteries solved in our lifetime because there is work going on now about the x-chromosome, for instance, one theory is that one of them gets 'turned-off' and so only one is manifest--but this is only a theory at this time.

Now if Hamburg was a mare, she would receive one x-chromosome from her dam--like he does, but she would also get another x-chromosome from his sire. This is why full brothers and sisters always are a little different genetically and is one of the reasons that the design of a full brother and sister in a pedigree is so effective, for it provides the entire genetic fabric of the target ancestor--all the sex-linked material as well as the basic DNA. So in this case, if Hamburg was a mare he would get one of Bourbon Belle's two x-chromosomes, from either Bonnie Scotland's dam or from Ella D RH; and once again we cannot determine at this time which one of them would come down to her.

Being a stallion, Hamburg would get the y-chromosome from his tail-male sire-line, from Hanover. So far in the research it appears that not much more than the sex determination arrives with this gene, but perhaps new discoveries will be made on this as well.

Mitochondrial DNA (mtDNA) only travels on the tail-female line to both sons and daughters; therefore it is always supplied by the mother--in this case to Lady Reel from Mannie Gray, not from Aerolite RH. The mtDNA has been identified as controlling energy conversion rates in the cells, and has much to do with respiratory efficiency, and these are important factors in any athlete, and so the consideration of the quality of the dam-line and the buildup of our broodmares is always a key factor in our success as sport horse breeders. In this case, Mannie Gray is about as good as it ever gets as she is also the dam of Domino et al--the fastest line, therefore the energy conversion factors she possesses and transfers are top rate. (Building up lines Hamburg et al with Domino et al, and their descendants into the background of pedigrees will create a critical mass in Mannie Gray).

With learning these principles we can make better decisions based on placement of certain ancestors in certain positions in our pedigree designs. With knowledge of the basic pedigree design we can then apply what we call Tesio Methods in both the evaluation of our proposed competition and breeding stock, and in the design of its breedings. 

[Note: when the breeding of a horse is given in text it is in a traditional format as well. In this case the writer would say Hamburg is by Hanover, out of  Lady Reel.]

* Tesio Methods:

A group of scholars, historians and scientists have put their minds and techniques to work in determining what practices are the most productive in designed equine matings. They began this quest by evaluating the pedigrees of the master breeder Federico Tesio, ergo 'Tesio Methods', and over the years they have tested and added to the findings. These methods are very useful for us as they enable us to read our pedigrees quickly to find the genetic power in them. Once we have become proficient in these techniques, it will allow us to not only recognize dominance in our stock and others, but will help when we choose to breed. It will identify the important ancestors for our goals and will empower us to plan matings that increase potency in those desired ancestors and their sport traits, therefore improve our sport horse products.

The scientist Clive Harper approached this task from the science disciplines, and in applying scientific parameters he developed statistics that show which pedigree patterns are the most effective in the production of top performance and breeding stock (Thoroughbred Breeder's Handbook). Because of the complexity in genetics these 'ideal pedigree patterns' are best used as  guides in our mating decisions, most pedigrees combine several of these factors in the layout--none of them can be assumed to guarantee a successful outcome on its own and must be considered in relation to the rest of the structure. They are important to us us because they have a higher percentage of success than standard practices (statistically). Further, with the continuous discoveries coming to us from the field of genetics we can add to these practices and surely come to understand why they are so effective.

This author uses Tesio Methods in her own breeding choices, and in evaluating the genetic power in other horses the horses throughout this website are analyzed via these techniques, and you will find this is a very handy tool for you to master. (see Tesio Methods and its links for further discussion and North American Sport Horse Breeder in depth discussion and step by step explanation how to apply it in your projects).

* Pedigree Design Components 

(short outline derived from Clive Harper's finding presented in his book: Thoroughbred Breeder's Handbook)

Multiple lines of an ancestor--this is simplistic, the more related ancestors you have in a pedigree, the closer the foal will be to that horse in type.

Sex-balance in the bloodlines has proven to be of the utmost importance in bringing the full benefits of the target ancestor down to the foal. So you would want a son and a daughter line of an important ancestor or a full or 3/4 sister to a sire, or a 3/4 brother through a daughter line for examples. Just repeating son lines of a sire begins to limit the genetic transmission.

Remote sex-balance: a more difficult design for the beginner, but historically and statistically it has proven to be effective. This is when one significant ancestor is present by just sons, and then is balanced by the presence of another important ancestor who is there with just daughters; this is strongest in positive results when both of the ancestors have similiar genetic weights. One outstanding example of this is seen in the pedigree of Lexington RH, who was born in 1850, yet he still holds the world stallion record of sixteen years as top sire. He carries Diomed sons 4x4x5 and Blaze daughters 8x9x8x7x10x10x10x10x10x9x10x10x9x10x10x10x10x9x9x10x10x9--these amounts in their generation positions are relatively equal in genetic weight (each generation further out is half the influence of the one closer in), and the history proves how incredibly powerful this design was.

Close siblings: full and 3/4 siblings, brothers and sisters, or sisters. or brothers, has proven to be the strongest potency builder we can employ.

Complexity in the lines: when targeting an ancestor, it has been demonstrated that to have variation in its expression increases the power. For instance, the power found in the full sisters Adioo ST and By Guy ST in Adios ST was enhanced by the presence of their 3/4 brother Chitwood ST who carried the opposite sex-balance for their sire and dam--complexity.

Repeat the breeding: once you have designed a mating that is very genetically promising it is better to repeat it at least once. Full siblings vary in their expression of the genes and there are many cases of one sibling being a super star in performance and his full sibling a dud. This can happen just through the normal process of how genes divide and only one half combines with that corresponding 1/2 gene of the mate, making variations extremely probably. So it is possible for a full sibling to receive the lesser half gene for a specific trait or traits. Repeating the breeding gives more insurance that the best combination is achieved in at least one of the offspring.

Performance versus stud duty: the pedigrees of successful performance horses can be different from great producers--often we find a 'male-leaning' pedigree in a top performer (minimal sex-balance in the lines), or a loosely structured lineage, however, we will find that they are not usually very successful in passing on the talent they displayed in their performance career.

* How Much Inbreeding?

Many of you after beginning learning Tesio Methods have expressed to me that you are concerned that you may be designing your pedigrees with too much inbreeding or line-breeding, and you want to know when it is too much. Inbreeding and to a lesser extent linebreeding concentrates whatever is there, good or bad, so it is very important that you understand the bloodlines you decide to build dominance in. Inbreeding of itself does not cause birth defects or diseases or faults, but if they are there in the genotype inbreeding makes them more likely to show up in the phenotype. It does this with the positive traits as well, which is why it is the best tool for building potency in the type or abilities we desire. For an example for you of a proven successful sport horse and stallion I have included the Standardbred Muscle Hill. He is a top racer and one of the best sires out there right now. You will find by examining his pedigree that it is not so much the amount of inbreeding but the quality of the inbred horses that matters, that if they are talented and sound you can get a winning horse like Muscle Hill--he is a superstar.                                                         (This article has been posted on Sporthorse-data site 5/27/2017)


Links to Other Articles



The Importance of Pedigree Study for Breeders
Sex Balance
The power in full and 3/4 siblings
Breed Potency into your Sport Horses
Pedigree Generation Position
Outline of Breeding Principles
Resources and References