Cheat Sheet: Understanding the D Locus (Dilution) in Self Rabbits

Although the D Locus (dilution) does affect rabbits who are Agouti or Tan/Otter, for this introduction let's stick to Self rabbits. As we know from this previous discussion of the A Locus, a Self rabbit is a solid-colored animal.

We will discuss the D Locus and how it affects Agouti and Tan rabbits in future scenarios.

The effects of the D Locus on chocolate rabbits is to lighten the color to lilac. It is exactly the same inheritance as black to blue: dilution is a simple recessive. However if you wish to add an element of complexity, you can "stack" genes; let's say you have two black rabbits. Visually, they are just black. However if both of them are heterozygous for dilution, AND both are heterozygous for the B Locus (recessive-Chocolate), you may get any of the following in a litter: black, blue, chocolate, AND lilac!

CLIFF'S NOTES FOR DILUTION ON SELF:

If you don't want to worry about Punnett squares or inheritance and just want to know what you will get through breeding, here is a basic rundown:

For this example, "Black" signifies a homozygous full-color (D/D) rabbit; "Black Carrying Blue" signifies a heterozygous for dilute (D/d) rabbit; "Blue" signifies a rabbit who is homozygous for dilution (d/d).

Black + Black = 100% Black. NO EXCEPTIONS.

Black + Black Carrying Blue = 50% Black, 50% Black Carrying Blue.

Black + Blue = 100% Black Carrying Blue. NO EXCEPTIONS.

Blue + Black Carrying Blue = 50% Black Carrying Blue, 50% Blue.

Blue + Blue = 100% Blue. NO EXCEPTIONS.

Black Carrying Blue + Black Carrying Blue = 50% Black Carrying Blue, 25% Black, 25% Blue.

Now let's consider rabbits homozygous for chocolate.

For this example, "Chocolate" signifies a homozygous full-color (D/D) rabbit; "Chocolate Carrying Lilac" signifies a heterozygous for dilute (D/d) rabbit; "Lilac" signifies a rabbit who is homozygous for dilution (d/d).

Chocolate + Chocolate = 100% Chocolate. NO EXCEPTIONS.

Chocolate + Chocolate Carrying Lilac = 50% Chocolate, 50% Chocolate Carrying Lilac.

Chocolate + Lilac = 100% Chocolate Carrying Lilac. NO EXCEPTIONS.

Lilac + Chocolate Carrying Lilac = 50% Chocolate Carrying Lilac, 50% Lilac.

Lilac + Lilac = 100% Lilac. NO EXCEPTIONS.

Chocolate Carrying Lilac + Chocolate Carrying Lilac = 50% Chocolate Carrying Lilac, 25% Chocolate, 25% Lilac.

Now do recall that these two Loci, the B Locus and D Locus, can "stack." Sometimes you can get a rainbow litter from two solid black rabbits! If you do get a recessive expression on a kit, it would be a good idea to mark it on the parents' pedigrees for future reference.

For example, I bred a blue doe (d/d) to a black buck carrying dilution (D/d). I expected black and blue kits only. To my surprise, there was also a chocolate kit in the litter!!! I hadn't know that BOTH my blue doe AND my black buck carried recessive chocolate!!! Thus my doe was d/d, B/b and my buck was D/d, B/b. Because that chocolate kit's mother was blue, but the kit was chocolate instead of lilac, she was genetically D/d, b/b. I marked on the pedigrees of each parent that they are apparently heterozygous for the B Locus! None of their ancestors on their pedigrees had been either chocolate or lilac, so the genes were "hidden" for over three generations.

Now let's look at how all of those genes "stack" together. If necessary, please refresh your memory of the A Locus, and the B Locus before we begin.

The blue doe in the above example is homozygous for self and dilution, heterozygous for chocolate. Thus, genetically, she is a/a, B/b, d/d. 

The black buck is homozygous for self, and heterozygous for dilution and chocolate. Thus, genetically, he is a/a, B/b, D/d.

The chocolate kit is homozygous for self and chocolate, heterozygous for dilution so, genetically, is a/a, b/b, D/d.

Starting to make sense? I hope so! 

Lastly, something to keep in mind is that the percentages listed above are for EACH KIT, not the litter as a whole unless the result is 100% foolproof. This means that each kit in a litter of, say, blue to black carrying blue mating, has a 50% chance of being blue. As such actual litter percentages may vary!

If you have any further questions, please feel free to comment below!

Cheat Sheet: Understanding the A Locus (Agouti, Tan/Otter, Self) in Rabbits

One of the first color genes to understand is the A Locus, which determines whether the hairs are banded or solid, and what base pattern the color expression of a rabbit is.

First the cheat sheets, then a discussion of "test breeding" to determine genetics; then all breeding percentages for the A Locus.

Most purebred rabbits have at least a three-generation pedigree which can give clues to a rabbit's genetics (or will outright state them; some breeders are excellent at documentation!). Remember that "A" is dominant to "at" and "a," meaning that an Agouti rabbit could be hiding the same or different genes for color...whereas since Self is recessive, ALL Self rabbits are homozygous.

If you do not know the parentage of a rabbit, you can "test breed." For test breeding the A Locus, it is always best to breed the rabbit-in-question to a Self rabbit. Here is an example: I had a doe who had extensive white patterning, and I couldn't visually discern if she was Agouti, Otter (Tan), or Self. I decided to test-breed her to determine her base colorings. I bred her twice, to two different Self bucks. With both bucks, she produced Otters (Tan pattern) as well as more Self rabbits. She did NOT produce any Agouti rabbits; since every rabbit has two genes per locus (one from each parent), it became clear she was an Otter, but heterozygous for Self. 

Had I bred her to a Self and she instead produced 50% Otter (tan) and 50% Agouti, it would prove she was Agouti.

There is something to mention about test breeding: results may vary. There is a reason I bred her twice to two different Self bucks: sometimes, you just get lucky. That doe was genetically an Otter (Tan) carrying Self, BUT she could have produced a litter of entirely-Self rabbits. You can flip a coin a hundred times, and you will rarely get Heads 50% of the time exactly! I usually recommend three test breedings unless the first or second breeding proves the genetics. If after three breedings, the results are consistent, it is safe to assume the rabbit's genetic color.

CLIFF'S NOTES FOR THE A LOCUS:

An Agouti rabbit can be one of three things, genetically: A/A, A/at, and A/a.

A/A = Homozygous Agouti. Two homozygous Agouti (A/A + A/A) will produce 100% homozygous Agouti. NO EXCEPTIONS. 

A/A (homozygous Agouti) bred to a homozygous Tan/Otter (at/at), 100% offspring will be Agouti carrying Tan (A/at). NO EXCEPTIONS.

A/A (homozygous Agouti) bred to a Tan/Otter carrying Self (at/a) will produce 50% Agouti carrying Tan (A/at), 50% Agouti carrying Self (A/a). Visually, the litter will be 100% Agouti; it will be unclear which kits carry Tan or Self unless test breedings are performed down the line.

A/A (homozygous Agouti) bred to a Self (a/a) will produce 100% Agouti carrying Self (A/a). NO EXCEPTIONS.

A/A (homozygous Agouti) bred to an Agouti carrying Tan/Otter (A/at) will produce 50% homozygous Agouti (A/A) and 50% Agouti carrying Tan/Otter (A/at). Visually, the litter will be 100% Agouti; it will be unclear which kits carry Tan unless test breedings are performed down the line.

A/A (homozygous Agouti) bred to an Agouti carrying Self (A/a) will produce 50% homozygous Agouti (A/A) and 50% Agouti carrying Self (A/a). Visually, the litter will be 100% Agouti; it will be unclear which kits carry Self unless test breedings are performed down the line.

at/at = Homozygous Tan (Otter). Two homozygous Tan/Otter rabbits (at/at + at/at) will produce 100% homozygous Tan/Otter. NO EXCEPTIONS.

at/at (homozygous Tan/Otter) bred to a heterozygous Tan carrying self (at/a) will produce 50% homozygous Tan (at/at) and 50% Tan carrying Self (at/a). Visually, the litter will be 100% Tan/Otter; it will be unclear which kits carry Self unless test breedings are performed down the line.

at/at (homozygous Tan/Otter) bred to a Self (a/a) will produce 100% Tan/Otter carrying Self. NO EXCEPTIONS.

at/a (heterozygous Tan/Otter) bred to a Self (a/a) will produce 50% Tan/Otter carrying Self (at/a) and 50% Self (a/a).

a/a (homozygous Self) bred to another Self (a/a) will produce 100% Self rabbits. NO EXCEPTIONS.

Lastly, something to keep in mind is that the percentages listed above are for EACH KIT, not the litter as a whole unless the result is 100% foolproof. This means that each kit in a litter of, say, heterozygous Agouti carrying self (A/a) to Self (a/a) mating, has a 50% chance of being Agouti carrying Self. As such actual litter percentages may vary!

If you have any further questions, please feel free to comment below!

Cheat Sheet: Understanding the Dutch Pattern in Rabbits

Unlike the "regular" broken gene/pattern and the English Spot pattern, the Dutch pattern requires homozygous rabbits to express fully as the belted Dutch pattern we know and love.

There are actually different "Dutch pattern genes" but they are beyond the scope of this series. This is a simplification in no small part to help breeders understand why crossbreds often lack the iconic Dutch pattern.

Please do be aware that even if a rabbit is genetically "perfect" the actual physical markings may vary. Mismarkings are common, and can be as simple as a tiny dot of color in the white belt or a lopsided blaze. Each animal must be judged on it's own merits. Also, color does not take into account conformation, which should be one of the most important aspects of breeding.

Crossbreeding Dutch is often done by people breeding for pets or for meat (Dutch are a shockingly meaty rabbit for their size). I personally have examined four different litters of rabbits where one parent was a Dutch (du/du) and the other was a non-Dutch/normal rabbit (Du/Du). In those breedings, roughly half of the kits had some sort of white marking, be it a white nose mark, a white foot, or a white blotch on the chest or back. However, the other half of the kits had no white whatsoever. 

For a rabbitry of small size looking for small meat rabbits, crossing Dutch to Florida Whites is an option. Depending on what genetics the Ruby Eyed White Florida rabbit(s) are hiding, the litters could be very unique and possibly colorful, especially if bred back to a Dutch parent or in subsequent sibling-to-sibling matings.

CLIFF'S NOTES FOR THE DUTCH PATTERN:

If you don't want to worry about Punnett squares or inheritance and just want to know what you will get through breeding, here is a basic rundown:

For these examples, "Dutch" signifies a homozygous classic-patterned Dutch rabbit; "Crossed" signifies a heterozygous-for-Dutch rabbit; "Solid" signifies a non-Dutch rabbit.

Dutch + Dutch = 100% Dutch. NO EXCEPTIONS.
Dutch + Cross = 50% Dutch, 50% Cross.

Dutch + Solid = 100% Cross. NO EXCEPTIONS.

Cross + Cross = 50% Cross, 25% Solid, 25% Dutch.

Cross + Solid = 50% Cross, 50% Solid.

Solid + Solid = 100% Solid. NO EXCEPTIONS.

Lastly, something to keep in mind is that the percentages listed above are for EACH KIT, not the litter as a whole unless the result is 100% foolproof. This means that each kit in a litter of, say, Dutch to Cross mating, has a 50% chance of being Dutch. As such actual litter percentages may vary!

If you have any further questions, please feel free to comment below!

Cheat Sheet: Understanding the English Spot Pattern in Rabbits

The English Spot is one of the most unique breeds of rabbit recognized by the American Rabbit Breeders Association (ARBA). Not only do they sport an iconic spotting/broken pattern, but they are one of a very few breeds who are judged while running. Here I will attempt to explain the basics of the Spot's spots.

As stated, there are many other modifiers that contribute to the markings, and are well beyond the scope of this discussion. 

CLIFF'S NOTES FOR THE ENGLISH SPOT PATTERN:

If you don't want to worry about Punnett squares or inheritance and just want to know what you will get through breeding, here is a basic rundown:

For these examples, "Broken" signifies a rabit with the ideal markings; "Solid" signifies a solid/non-spotted rabbit; "Charlie" signifies a homozygous/minimally-marked rabbit.

Broken + Broken = 50% Broken, 25% Solid, 25% Charlie.

Broken + Solid = 50% Broken, 50% Solid.

Broken + Charlie = 50% Broken, 50% Charlie.

Charlie + Solid = 100% Broken. NO EXCEPTIONS.

Charlie + Charlie = 100% Charlie. NO EXCEPTIONS.

Solid + Solid = 100% Solid. NO EXCEPTIONS.

Lastly, something to keep in mind is that the percentages listed above are for EACH KIT, not the litter as a whole unless the result is 100% foolproof. This means that each kit in a litter of, say, Broken to Solid mating, has a 50% chance of being Broken. As such actual litter percentages may vary!

If you have any further questions, please feel free to comment below!

Cheat Sheet: Understanding Mane Genetics in Lionhead Rabbits

The mane is one of the hallmark characteristics of the Lionhead breed but some people are trying to produce "Lion-lops" and other such crossbreds. Often the first-generation crossbreds have insufficient manes; indeed some purebred Lionheads have sparse or nonexistent manes! This seeks to explain the basics of mane inheritance.

Unfortunately I have seen a number of unscrupulous breeders on questionable websites selling Lionhead and Lionhead cross kits and claiming that they are double maned, when one or both parents are maneless. Please do not fall for this! There are many quality Lionhead breeders out there, please purchase from ethical breeders who are honest about their rabbits' manes.

That being said, there is NOTHING wrong with a single-maned Lionhead! Conformation and temperament are important characteristics, and a rabbit that is otherwise of excellent quality can be a boon to a breeder, especially if the single-mane is bred to double-manes. 

Another factor is that there are other genetics at play which will help determine mane fullness and length. Obviously purchasing a double-maned kit from exceptionally fluffy bloodlines will increase the chances of a full mane. Conversely, some double-manes from sparse-furred bloodlines will be barely more fluffy than a single-mane. Fur quality is a complex subject that is far above the scope of this oversimplified page.

A note about Lionhead Kits:

CLIFF'S NOTES FOR LIONHEAD MANE GENETICS:

If you don't want to worry about Punnett squares or inheritance and just want to know what you will get through breeding, here is a basic rundown:

For these examples, "Double Mane" signifies a homozygous double-maned Lionhead; "Single Mane" signifies a heterozygous single-maned Lionhead; "No Mane" signifies a rabbit without the genes that govern manes.

Double Mane + Double Mane = 100% Double Mane. NO EXCEPTIONS.

Double Mane + Single Mane = 50% Single Mane, 50% Double Mane.

Double Mane + No Mane = 100% Single Mane. NO EXCEPTIONS.

Single Mane + Single Mane = 50% Single Mane, 25% Double Mane, 25% No Mane.

Single Mane + No Mane = 50% Single Mane, 50% No Mane.

No Mane + No Mane = 100% No Mane. NO EXCEPTIONS.

Lastly, something to keep in mind is that the percentages listed above are for EACH KIT, not the litter as a whole unless the result is 100% foolproof. This means that each kit in a litter of, say, Double Mane to Single Mane mating, has a 50% chance of being Double Maned. As such actual litter percentages may vary!

If you have any further questions, please feel free to comment below!

Cheat Sheet: Understanding Recessive Chocolate Inheritance in Rabbits

For the purposes of understanding recessive Chocolate, I am assuming that all non-Chocolate rabbits are black. It is best to understand simple recessive genes before adding the pressures of other color modifiers such as Dilution. Such topics will be entertained at a future time.

CLIFF'S NOTES FOR RECESSIVE CHOCOLATE:

If you don't want to worry about Punnett squares or inheritance and just want to know what you will get through breeding, here is a basic rundown:
For these examples, "Chocolate" signifies a homozygous recessive-Chocolate rabbit; "Black" signifies a homozygous Black rabbit; "Black Carrying Chocolate" signifies a rabbit who is heterozygous for Black and Chocolate genes.

Chocolate + Chocolate = 100% Chocolate. NO EXCEPTIONS.

Chocolate + Black Carrying Chocolate = 50% Black Carrying Chocolate, 50% Chocolate.

Chocolate + Black = 100% Black Carrying Chocolate. NO EXCEPTIONS.

Black Carrying Chocolate + Black Carrying Chocolate = 50% Black Carrying Chocolate, 25% Black, 25% Chocolate.

Black Carrying Chocolate + Black = 50% Black Carrying Chocolate, 50% Black.

Black + Black = 100% Black. NO EXCEPTIONS.

Remember, Chocolate is recessive to Black!

Lastly, something to keep in mind is that the percentages listed above are for EACH KIT, not the litter as a whole unless the result is 100% foolproof. This means that each kit in a litter of, say, Chocolate to Black Carrying Chocolate mating, has a 50% chance of being Chocolate. As such actual litter percentages may vary!

If you have any further questions, please feel free to comment below!

Cheat Sheet: Understanding the Dwarfism Gene in Rabbits

Be aware that dwarf genes are in many breeds and in fact are desirable for show purposes in a number of smaller breeds, such as Mini Rex, Netherland Dwarf, Jersey Wooly, Holland Lop, and Lionheads, just to name a few!

A quick discussion on breeding dwarf-to-dwarf:

Do not be hasty to judge a breeder who does dwarf-to-dwarf matings, because usually it is the dwarf rabbits who are more correct for the breed and likely have a show record, whereas the larger false-dwarfs might never see a show table in their lives. I know that when I bred Mini Rex, I had very limited space and could only have a few rabbits; thus every breeding rabbit I owned by necessity had to also have a show career. I simply did not have the space nor time to devote to false dwarfs. I personally preferred to cull peanuts within a day to three days of birth, but some breeders choose to let nature take it's course and thus some rare peanuts survive almost to weaning. No peanut survives past weaning age, however.

Also, bear in mind that some rabbits are true dwarfs but do not look like it! I know of a breeder who had a doe that was assumed to be a false dwarf...until she produced a peanut when bred to a dwarf buck! This is uncommon (most genetically true dwarfs are visibly smaller and shorter ears, often with a more blocky head) but not unheard of.

Here are some photos of peanut kits next to normal kits, to show both how grossly undersized they are and also to highlight their common deformities.

Mini Rex littermates, showing size difference between peanut and normal/viable kit.

From the Wintertime archives.

Above is a shockingly well-formed peanut kit next to a normal littermate. Though this peanut is less deformed than most, he is still much smaller than the normal-sized, viable kit. Incidentally, the normal kit in this picture is a proven genetic dwarf (heterozygous of course).

Deceased runt versus deceased and deformed peanut, side by side.

From the Wintertime archives.

Above are two day-old kits, both born alive but both of whom died in their first night. The kit on the (viewer's) left is a very, very small runt but still has normal body proportions. This picture simply highlights the physical differences between normal, viable kits and their deformed peanut brethren. As you can clearly see, the peanut kit on the (viewer's) right is very deformed, typical of peanuts; note the severely underdeveloped hindquarters, domed head, and excessively tiny and underdeveloped ears. 

Peanut kit next to her normal, viable littermate.

Photo by S. Sousa, used with permission.

Some less-deformed peanut kits survive for several weeks; as long as they are able to adequately nurse, they may continue to live. Some extremely lucky peanut kits grow old enough to open their eyes and explore with their littermates! Seen above is the oldest, most well-developed peanut I have been able to find; she is pictured here with her normal, viable littermate. Even so, notice how different her head is shaped, and how tiny her ears are! In this photo, these kits are almost ready to be weaned from their mother- that is the cutoff age for peanuts. Some theorize that their digestive systems simply cannot cope with solid foods. The exact method of demise for less-deformed peanut kits is, as far as I know, unknown.

Look at how incredibly tiny she is!!

Photo by S. Sousa, used with permission.

The photo above shows just how incredibly small this miracle peanut kit really is!!! Imagine a six to eight week old rabbit, still half the size of the littermates or smaller! Hard to imagine, I know!!!

CLIFF'S NOTES FOR DWARFISM:

If you don't want to worry about Punnett squares or inheritance and just want to know what you will get through breeding, here is a basic rundown:

For these examples, "True Dwarf" signifies a heterozygous and viable dwarf rabbit; "False Dwarf" signifies a rabbit that does not have dwarfism genes; "Peanut" signifies a homozygous and non-viable dwarf kit.

True Dwarf + False Dwarf = 50% True Dwarf, 50% False Dwarf.

True Dwarf + True Dwarf = 50% True Dwarf, 25% False Dwarf, 25 % Peanut.

False Dwarf + False Dwarf = 100% False Dwarf. NO EXCEPTIONS.

Lastly, something to keep in mind is that the percentages listed above are for EACH KIT, not the litter as a whole unless the result is 100% foolproof. This means that each kit in a litter of, say, True Dwarf to False Dwarf mating, has a 50% chance of being True Dwarf. As such actual litter percentages may vary!

If you have any further questions, please feel free to comment below!

Cheat Sheet: Understanding the Vienna Gene in Rabbits (Blue Eyed Whites)

Before we get to the cheat sheets, you need to remember that a Blue Eyed White will "hide" the base color of the rabbit in it's homozygous form. Thus a "black" rabbit who has two copies of the Vienna gene (V/V) will appear white with blue eyes.

Also, I cannot stress it enough, the Vienna gene in it's heterozygous form (V/v) might not be visually expressed, so it can pop up many, even dozens of generations later. Because of this, it is recommended that if there is Vienna in a rabbit's background, it be noted on their pedigree even if the last known Vienna carrier or BEW is many generations back. Full disclosure, transparency, and honesty are appreciated when dealing with this gene locus.

Also it has come to my attention that many people use the lowercase v to signify the Vienna gene, and the capital V to signify non-Vienna rabbits. I am SO sorry for any confusion that this has caused. As such please take this discrepancy into account when discussing genetics!!!!

CLIFF'S NOTES FOR VIENNA/BLUE EYED WHITES:

If you don't want to worry about Punnett squares or inheritance and just want to know what you will get through breeding, here is a basic rundown:

For these examples, the abbreviation "BEW" signifies a Blue Eyed White; "Vienna Carrier" signifies a rabbit that has one copy of the Vienna gene; "Non-Vienna" signifies a rabbit that has no Vienna genes.

BEW + BEW = 100% BEW. NO EXCEPTIONS.

BEW + Vienna Carrier = 50% BEW, 50% Vienna Carrier.

BEW + Non-Vienna = 100% Vienna Carrier. NO EXCEPTIONS.

Vienna Carrier + Vienna Carrier = 50% Vienna Carrier, 25% Non-Vienna, 25% BEW.

Vienna Carrier + Non-Vienna = 50% Vienna Carrier, 50% Non-Vienna.

Non-Vienna + Non-Vienna = 100% Non-Vienna. NO EXCEPTIONS.

Remember, a Vienna Carrier or BEW bred to a Non-Vienna will NEVER PRODUCE BEW!!!! 

Also remember that while many Vienna Carriers have white markings and may even have blue eyes, there are far more that do not visually express the gene AT ALL, so you cannot tell just by looking at a rabbit if they are a Vienna Carrier or not. This is why making notation of BEW or Vienna heritage possibilities on pedigrees is so important!

Another thing to consider is that many breeders AVOID breeding Chocolate into BEW programs due to undesirable eye coloration.

Lastly, something to keep in mind is that the percentages listed above are for EACH KIT, not the litter as a whole unless the result is 100% foolproof. This means that each kit in a little of, say, BEW to Vienna Carrier mating, has a 50% chance of being BEW. As such actual litter percentages may vary!

If you have any further questions, please feel free to comment below!

Cheat Sheets: Understanding the Broken Pattern Gene in Rabbits

Before we get into the heart of the matter, I need to remind you that the broken pattern is just that: a pattern, not a base color. Broken can overlay on "top" of any other color; a black rabbit with the broken pattern will be a broken black; likewise, an otter-colored rabbit with the broken pattern will be a broken otter. The broken gene merely dictates the extent and pattern of white over the base color.

Now, onto the "cheat sheets" for broken patterns:

CLIFF'S NOTES FOR BROKENS:

If you don't want to worry about Punnett squares or inheritance and just want to know what you will get through breeding, here is a basic rundown:

For these examples, "Broken" indicates a broken-patterned rabbit, "Solid" indicates a non-broken-patterned rabbit, and "Charlie" refers to a minimally-colored broken-patterned rabbit that is genetically homozygous.

Broken + Solid = 50% Broken, 50% Solid.

Broken + Broken = 50% Broken, 25% Solid, 25% Charlie.

Charlie + Solid = 100% Broken. NO EXCEPTIONS.

Charlie + Broken = 50% Broken, 50% Charlie.

Solid + Solid = 100% Solid. NO EXCEPTIONS.

Remember that a TRUE Charlie will NEVER, EVER produce a non-broken rabbit. There ARE some genes (such as Ruby Eyed White or Blue Eyed White) that may hide the broken pattern but the rabbit will still be genetically broken and will produce as such.

Lastly, something to keep in mind is that the percentages listed above are for EACH KIT, not the litter as a whole unless the result is 100% foolproof. This means that each kit in a litter of, say, Broken to Solid mating, has a 50% chance of being Broken. As such actual litter percentages may vary!

If you have any further questions, please feel free to comment below!