Genetics 101- Mini Rex are the breed of discussion, but this applies to ALL BREEDS!!! Just remember to change some of the names to suit your breed, such as changing the color name Castor to Chestnut (all breeds), Sandy (Flemish) or Copper(Satin coated animals).
The Chinchilla Light gene "c(chl)" covers the aspect of our true Shaded varieties. When a color has the Chin Light gene in effect, it remains the same base color (Black, Blue, Chocolate, or Lilac), but the recessive combination of gene changes it from a self colored animal to a shaded one. Black becomes Sable, Blue becomes Smoked Pearl, Chocolate becomes a Chocolate Sable, and Lilac becomes 'Pewter'. Although this gene is called "Chin Light", it really has nothing to do with the normal Chinchilla coloration, and would be better named the SHADING GENE.
In the order of Dominance, the Chin Light gene offers subtle differences. It is a gene that when present and dominant show the correct color properly shaded into a Shaded animal. When the genes are paired (homozygous), it becomes a new variety - Seal. :
c(chl)*- Sable, and Smoke varieties
c(chl)c(chl) - Genetic Seal
c(chl)* with umbros (darkening) modifiers- Dark Sable, looks like Seal
A rabbit has 2 genes on each series, and one is given from each parent. For a said color to be shown on a kit, one of its parents must have given it to the offspring. *The Dominant gene is the one that you "SEE"*, also know as the rabbits Phenotype. When both genes are known, that is call the Genotype. A rabbit with 2 identical genes is called Homozygous, and one with 2 different genes is call Heterozygous.
A rabbit will have its "Visual" gene and then can carry another identical one(Homozygous), or any one BELOW it on the series, but NEVER ONE ABOVE IT...that would mean that the rabbit is NOT the color you said it was in the first place (i.e.: A Lilac carrying Black. The Black is DOMINANT, so the said "Lilac" rabbit would be Black).
Genetic Seal c(chl)c(chl) - This is the ONLY correct genotype for a Genetic SEAL. Rabbits appearing Seal in coloration, and have produced Sables, but have a REW or Himalayan parent are in fact DARK SABLE. Ignorance to this fact can potentially ruin anothers breeding program.
Sable c(chl)* - Sables must have a recessive gene present. It can only be REW or Himalayan. In order for the Sable shading to correctly present itself, the recessive gene must be present. In the case where a rabbit shows minimal shading, but there is no Himi or REW on the pedigree, the animal must be test bred to prove it is not a genetic Seal.
Self Chinchilla c(chd)* - The Chinchilla dark gene can also come into play. The resulting animal with a Chin Dark gene will sometimes resemble a Seal, but it will NOT breed like one. If there are many Chinchillas or "Seals" out of Chinchillas on the pedigree, the rabbit more than likely is not a Seal, but in fact, a Self Chinchilla. This is gone into further detail within the Breeding Chins seminar.
Some Examples of this in "color talk":
An example of a genetically impossible breeding with the Chin Light gene:
Seal X REW = Seal(The REW has no Chin Light gene to offer*).
*I am making a notation of this genetic impossibility because many people who are just starting in rabbits are purchasing more stock than breeding them. Each and every person CAN BECOME familiar with their genetics enough that they can eventually call the shots, and make their selection of replacement breeding stock a little more effectively....ON THEIR OWN!!!
The percentages of a given color that are shown on many websites and genetics books are not a percent per litter, it is the chances that EACH KIT has of being a certain color or pattern. Such as, a Black to Black cross and they both have a Blue parent, each KIT has a 50% chance of being a Blue, not 50% of the litter. With that genetic average, the same cross could potentially produce 100% Blues. Murphy's Law tends to prevail, and if you are trying to produce that particular color, it will stay recessive almost indefinitely...LOL!
By looking at the pedigree, you may be able to Genotype your animals.
A punnet square below illustrates this cross, and you can substitute other crosses accordingly.
Please note that there is NO TALK OF TORTOISE within the SHADING GENE!! Tortoise is NOT a shaded variety, it is a non-extension variety - a self colored Red, where Blue Tortoise is a self colored Fawn.