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Color genetics in plain language
One of the most common questions when anxiously waiting for puppies is what color the future puppies will be. That's why I've decided to write this lengthy explanation here about how colors are inherited, so that those interested can familiarize themselves with it.
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The letters and numbers in parentheses tell how the characteristic or color is expressed in the registry book and pedigrees.
Red often shows a pattern, even if it isn't there genetically
Probably everyone has learned in elementary school that presumed males have XY chromosomes and presumed female XX chromosomes.
The color of cats is inherited on the X chromosome, and there are two options as to which color it is, and these are black or red. This is why turtles are always female (unless it's a genetically defective litter with two X chromosomes or some other mutation), because only females have two X chromosomes.
This would mean that two black cats would always get black kittens and two red cats would get red ones, simplified like that. A tortoise-colored female, on the other hand, could have both black, red, and tortoise-colored puppies. And a black and a red cat could get tortoise (f) colored females and mother colored (black, n or red, d) collie boys.
So far, plain and simple, if maybe a bit confusing.
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Then the question arises, what about all those other colored cats?
Like white or white-spotted.
White spotting is a dominant characteristic, i.e. if either mother or father has white, it is most likely that the puppies will also have white. However, a cat can also be monochromatic (this is not related to turtle coloring, but in this context it is also referred to as monochromatic even if the cat has two colors, so to speak - red and black), even if it has white. In this case, two of the white spots can have solid (i.e. monochromatic = not white) puppies.
There are many extents of white spotting, in the first version the white is perhaps only on the paws and a little on the chin, in the next version it has spread to the neck and under the belly (both are recorded in the register book 09, unspecified amount), perhaps also to the end of the tail, after this it forms a collar around the neck and perhaps a spot or two on the back (03, bicolor), the next version already contains more white than color, so the cat has only color spots (02, harlequin) and the last version has color only on the head and tail, maybe also one spot somewhere on the body (01, van) .
The whiteness of a completely white cat can be caused by several factors, either the cat inherits a dominant white color that covers the other colors (i.e. the cat is phenotypically white, but the genotype is black, red or tortoise, which is completely covered by white) or it is albino (there are also a few variations of this) or the cat is strongly white-spotted, in which case the spots cover all the color underneath, in which case the parents probably also have a lot of white, but also colored areas.
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A cat that inherits dominant white (w) also inherits colors other than white, but since it is a dominant gene, the kitten only needs a gene from one parent and is then completely white. The dominant white gene is special in that it can also cause deafness in the cat and also affects the color of the eyes.
An albino cat's fur, on the other hand, lacks pigment completely, usually their eyes are blue, but also full albino - that is, the existence of red-eyed cats has been reported.
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And striped cats then? That is, agoutis.
Patterning, or agouti, is a dominant feature in cats, so it is enough if one of the parents is striped, and the puppies are more likely to be patterned, but they can also carry no pattern, in which case two striped cats can have a non-striped, i.e. non-agouti, puppy. But then again, two non-patterned cats can't have patterned kittens (although there is something called a ghost pattern - in that case, genetically it is not patterned, but it looks patterned in phenotype, it occurs especially in red cats).
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There are several different types of patterns, they are called tabby patterns - the most obvious pattern is the classic tabby (22) formed by large patches, "bull's eyes", the pattern of a cat with smooth stripes is instead a tiger (23) and the more common is the spotted cat, which is boringly just spotted (24). Rarer in Norwegian forest cats, but very typical in some breeds is ticked instead (25), where the pattern is no longer even clear, but the fur is two-colored, i.e. ticked. If there are fewer colors, and therefore the pattern cannot be determined, it is called an undefined pattern (21). The inheritance of the type of these patterns is a more complicated genetics, which you have to research for yourself, I won't go into that here. ​
What about the grays then, i.e. dilution.
It's a different gene, and like white spotting, it's not inherited in the X cell, which converts the head color (red or black) into a different appearance. One could imagine that it is a filter gene that lightens an existing gene; black becomes blue (a, i.e. that gray shade) and red becomes creme (e, as the word says, cream-colored), and a turtle becomes a blue turtle (g). This gene is called the dilution gene.
The dilution gene is a recessive trait, which means that a cat can carry the gene without showing it externally. The external essence is called the phenotype and the genetic characteristic the genotype. In order for such a receding gene to be visible externally in the fight, i.e. in the phenotype, it must come from both parents.
I imagine that we have one black cat that does not carry the gene in question, but it has kittens with a blue cat, these kittens would all be carriers, but none of them would show this trait externally, so the kittens would be black._cc781905 -5cde-3194-bb3b-136bad5cf58d_
When such a cat then has kittens with another carrier or dilution cat, the kittens can be dilution cats or carriers. The kittens of only two dilution cats are all dilution cats.
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What about a cat whose undercoat is lighter than the main coat? That is, smoke and silver.
The fur of smoke and silver cats (s) generally appears white, with a colored head. So it can be said that the base is white and the top is colored. There are variations of silver and smoke everywhere, from cats on an almost imperceptible pale base to almost white ones.
Cats with no patterns are called smoke and cats with patterns are called silver, but it's the same gene.
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This gene is also like a pattern gene, i.e. dominant, in which case it is enough that only one of the parents carries the gene so that the puppies can be smoke or silver in color, but thus the other parent must be silver or smoke in order for the puppy to get this coloring in its coat.
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There is also a variant of silver called gold (y). Here, the base color is very different from silver, the color being more of a warm apricot or cream. Otherwise, the gene is similar and has the same style as silver.​
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And then amber.
Amber is an interesting color because it has been reported to occur only in Norwegian forest cats and the puppies are born resembling black, red or tortoise color and start to get more reddish, amber (amber in English) or golden yellow tone as they grow._cc781905-5cde-3194-bb3b- 136bad5cf58d_
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Amber (t) is a receding feature like dilution. So both parents must at least carry the gene for the puppy to be amber-colored.
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There can be different combinations of all these above-mentioned features. For example, the cat can be a silver blue tortoise amber tabby on white, so there are a lot of variations of looks.
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I hope this opened things up at least a little, unfortunately I can't explain this more simply than this, and this isn't even everything. There are characteristics that are not accepted in the Norwegian forest cat, such as lilac, cinnamon or masks, the inheritance of which I will not open here. However, more information can be easily found with a little Googling.