There are no guarantees in breeding, but those with a thorough understanding of genetic diversity have long used linebreeding and hybrid vigor to hedge their bets.
Linebreeding, also called inbreeding, is designed to make individuals more homozygous for the desired traits we want to preserve in a breeding program. Homozygosity appears when two identical alleles (genes) appear together at a given location on the chromosome.
Inbreeding increases the possibility of homozygosity overall in the foals produced. This is how a breed is formed and controlled, by passing certain traits on generation after generation. It gives the breed and breeder the ability to set traits for a certain bloodline.
Hybrid vigor is the phenomenon that takes place when we breed two “unrelated individuals” that produce outstanding foals. A higher level of hybrid vigor can occur when one or both of the individuals being mated are inbred but unrelated.
The crossing of unrelated inbred individuals is used to achieve genetic diversity, and genetic diversity has shown to be a key to the improvement of our horses. Thus, when you see this kind of linebreeding within the pedigree, you know the breeders were striving to improve the next generation through genetic diversity by crossing two unrelated bloodlines.

Genetic Diversity: Super Marioo
There was quite a “bang” when Super Marioo picked up the 2019 National Reining Horse Association (NRHA) Futurity Levels 4, 3 and 2 Open titles. Ridden by Equi-Stat Elite $1 Million Rider Cade McCutcheon during the young trainer’s first year as a professional, the stallion banked around $200,000 at the event — pushing his earnings as a 3-year-old to $243,701.
Super Marioo (Gunnatrashya x HA Chic A Tune x Smart Chic Olena) is owned by Story Book Stables and was bred by the Hillis Akin Family Partnership. When we look at Super Marioo’s pedigree, we see no duplication of ancestors that his sire and dam share within five generations. But, his sire and dam each have duplications of ancestors in their respective pedigrees.
Let’s take a look at how these concentrations of blood through inbreeding contributed to Super Marioo’s pedigree.
Gunnatrashya (Colonels Smoking Gun [Gunner] x Natrasha x Trashadeous) was the 2009 NRHA Futurity Open Champion, All American Quarter Horse Congress Futurity Open Champion and the 2010 NRHA Derby Open Champion. He is now a $3.6 million sire and the sire of multiple NRHA Futurity champions. (His other is ARC Gunnabeabigstar, a 2011 stallion out of Wimpys Little Chic.)
Gunner (Colonelfourfreckle x Katie Gun x John Gun) was an NRHA Futurity Open Reserve Champion, and he is Equi-Stat’s No. 2 leading sire of reining horse money-winners. Natrasha (Trashadeous x My Royal Enterprise x Be Aech Enterprise) was an NRHA Futurity finalist in 1996 and is now the dam of horses with earnings of $461,145.
When we step back and look Natrasha’s pedigree, we see that Trashadeous was sired by Be Aech Enterprise. This gives Natrasha a breeding pattern of 2 X 2 to Be Aech Enterprise, making her inbred to this stallion.
HA Chic A Tune is an unshown mare that is the dam of horses with earnings of $335,000-plus, with her foals also earning 256 American Quarter Horse Association (AQHA) points. Her second leading money-winner is HA The Looney Tune (by Im Chairman), an AQHA Level 2 Reining Reserve World Champion.
HA Chic A Tune’s sire is Smart Chic Olena (Smart Little Lena x Gay Sugar Chic x Gay Bar King), who is the No. 4 all-time leading sire of reining horse money-earners and the No. 2 leading sire of reined cow horse money-earners, according to Equi-Stat.
Gay Sugar Chic is out of Chicy Little, by Frisco. Her dam is Bay Sugar Chic, by Frisco. This gives Chicy Little a breeding pattern of 1 X 2 to Frisco.
Tune Miss Red is the dam of HA Chic A Tune, and she was sired by Mr Baron Red (Red Baron Bell x Two Eyed Patti x Two Eyed Jack). He was an AQHA World Show Superhorse.
Tune Miss Red is Superior in heading and heeling, with 143 AQHA points. Her foals have earnings of $80,032 recorded in Equi-Stat, with five offspring who have their performance Registers of Merit — including 2001 NRHA Futurity Intermediate Non-Pro Champion Da Chics Tune. Da Chics Tune is a full brother to HA Chic A Tune.
Jack’s Tune (Two Eyed Jack x Little Music x Arthur Howard) is the dam of Tune Miss Red. Jack’s Tune is an AQHA Champion with Superiors in halter and Western pleasure, as well as 376 AQHA points overall. This gives Tune Miss Red a breeding pattern of 3 X 2 to Two Eyed Jack.
As we have highlighted, Natrasha boasts a 2 X 2 breeding pattern to Be Aech Enterprise, while HA Chic A Tune traces back through Chicy Little with the 1 X 2 breeding pattern to Frisco. Tune Miss Red, Super Marioo’s maternal granddam, represents a 3 X 2 breeding pattern to Two Eyed Jack.These breeding patterns are an excellent example of how breeders successfully use linebred individuals to increase hybrid vigor in the foals produced.