Cat colours for starting breeders

Credits go to Kathy from (former cattery Zero Pelagio) for this beautiful and clearly written text.

Being a starting breeder myself, I know that feline genetics is a maze of symbols and jargon that are not very evident for a novice, so I want to try and explain a few basic principles in this article.
I noticed that breeders sometimes ascribe colours to their kittens which they simply can’t have according to the laws of genetics, I’m hoping this article can be of some assistance in avoiding those mistakes.
I’ll try to explain the most important words you often see when reading about genetic traits:

Chromosomes.
Every animal has numerous pairs of chromosomes. Each pair is formed by one chromosome that is inherited from its mother, and another chromosome which is inherited from its father. So mother and father each pass on half of their chromosomes to their offspring, so that this offspring can construct a complete set with it. One of these pairs of chromosomes determines the gender. An X-chromosome is feminine, a Y-chromosome is masculine. Females always carry two X-chromosomes, so the pair of chromosomes that defines the female sex looks like this: XX. The male pair of chromosomes looks like this: XY. A female has two X’s and can only pass on one X. A male has an X as well as a Y, so he can pass on an X to produce a daughter (together with the mother’s X it forms XX) or he can pass on a Y to produce a son (together with the mother’s X it forms XY)
So the father determines the sex of the kittens:

Mother  +  father   =  offspring            or            mother  +  father   = offspring
XX     +    XY    =     XX                                   XX      +     XY    =    XY

The bold and underlined letters symbolise the chromosomes that are passed on. Which one the mother passes on is of no significance to the gender of the offspring, since it is always an X.
The mother determines the colour of the male kittens in each litter. For example: a cream mother and a blue father can only produce cream male kittens together. The female kittens will get their colour from both mother and father, and will be blue-cream.

Homozygous versus heterozygous.
An animal is called homozygous for a certain trait (this can be coat colour, of coat structure e.g.), if it has two identical alleles in the pair of chromosomes that is responsible for that specific trait. Alleles are genes that have the same locus (location) on a chromosome. When the two alleles are identical, this animal cannot pass on any other allele than that one. That is why we call it pure bred: all offspring will get this trait as passed on by that parent.
An animal is called heterozygous for a certain trait when the two alleles are different. It can pass on one or the other, and we can never be certain which one it will be beforehand.

Dominant versus recessive.
A dominant trait will always be obvious in the physical appearance of an animal. For example: in humans “having brown eyes” is dominant towards “having blue eyes”. So you need only one allele for brown eyes to actually have brown eyes. Because everyone gets one allele from each of his parents, someone with brown eyes can either have two alleles for brown eyes, or one for brown and one for blue, which is suppressed. Brown is dominant, so in the physical appearance you will only notice the brown eyes. But that person then “carries” the gene for blue eyes.(what you see on the outside is called the phenotype, what is carried on the inside is called the genotype) Two people with brown eyes who both carry the gene for blue eyes can therefore have a child with blue eyes, if they both pass on their gene for blue eyes.
A person with blue eyes will always have two alleles for blue eyes, since blue is a recessive trait. So two parents with blue eyes can never have a child with brown eyes.
Two animals with a recessive trait can never have offspring with a dominant form of that same trait.

The Punnett square.
This method is being used to calculate statistically what a litter could look like. A diagram is made where at the top the father’s properties are placed and to the left the mother’s. All the genes are then split and passed on in turns, so that, with a simple diagram, you can see all four possibilities.
Let’s illustrate with the example of the brown and blue eyes. Brown eyes are symbolised with a capital B, blue eyes with a small b.

1. Supposing that father and mother are both homozygous for brown eyes:

All children receive two genes for brown eyes, so they will all have brown eyes.

1. Supposing that father is homozygous for brown eyes, but mother carries the gene for blue eyes:

I worked with bold and italic letters in this diagram, so you can clearly see which gene for which trait is passed on by whom.
Mother first passes on the gene for brown eyes (B), and so does father (B). Then mother passes on the gene for brown eyes again (B) and so does father (B). Then mother passes on her gene for blue eyes (b) and father passes on a gene for brown eyes (B), and as a fourth and last possibility mother’s gene for blue eyes (b) is combined with father’s other gene for brown eyes (B).
Now we see that two out of four children are homozygous for brown eyes, the other two children will have brown eyes, but both will carry the gene for blue eyes.

1. Supposing both parents are heterozygous; they both carry the gene for blue eyes, but both have brown eyes, therefore they each have one gene for brown eyes:

Here, too, all combinations are made clear:
Mother first passes on her gene for brown eyes (B) and so does father (B). Then mother passes on her gene for brown eyes (B) and father passes on his gene for blue eyes (b).
Next mother passes on her gene for blue eyes (b) and father passes on his gene for brown eyes (B). And as a last possibility both mother and father pass on their genes for blue eyes (bb).
Here we can see that only one child is homozygous for brown eyes, two children have brown eyes but are blue eye-carriers, and one out of four children has two genes for blue eyes, thus has blue eyes itself.

1. Supposing mother has blue eyes, and father has brown eyes but is a blue eye-carrier:

Here we can see that two children have brown eyes and are blue eye-carriers, and the other two children each have two genes for blue eyes, so they have blue eyes.

1. Supposing both mother and father have blue eyes, the square will look like number 1) but all the genes for brown eyes (B) will be replaced with genes for blue eyes (b) and all children will have blue eyes.

F1, F2, F3, etc.
These letter- and number combinations are used to indicate in how many generations a certain trait has been passed on. An example: the nakedness of the Sphynx is recessive, or “inferior” to the hairs of a normally furred cat. When a furred queen is mated to a naked stud, all kittens will be furred. The mother has two alleles for fur, so she can only pass on an allele for fur. The father has two alleles for baldness, so he can only pass on an allele for baldness.
All kittens in this litter will be furred, but all will also carry one gene for the Sphynx’s nakedness. This is called the F1 generation.
When a queen from this F1 generation, who is furred, is mated to another Sphynx male, the furred queen, following the laws of statistics, will pass on the allele for fur to half of her kittens, and the allele for baldness to the other half. Those kittens receiving the allele for fur from their mother will, again, be furred, although they are getting an allele for nakedness from their father. The other kittens will receive an allele for nakedness from both mother and father, so they will be naked themselves. This is the F2 generation, which can have both furred and naked kittens.
When a naked kitten from that F2 generation is mated to another naked cat, only naked kittens can come out, because all cats can only pass on one of both alleles for nakedness that they carry. This is called the F3 generation.
Usually, by selective breeding, naked kittens will become balder with each generation that separates them further from their hairy ancestors.
If the first, hairy, mother is mated to a homozygous Sphynx, then all kittens will carry the gene for baldness, and when mated to another homozygous Sphynx, will produce bald kittens in the F2 generation that are already homozygous, and therefor completely bald.

Note: new regulations define a cross between a normally coated cat and a Sphynx as EXP (Experimental) and not F1. Only the next generation is called F1, and so forth.

Dilution/Clotting.
There are two “main colours” in cats, namely black and red. These are dominant colours. Because of the effects of dilution or clotting (two different influences) these colours can change: black to blue, caramel, chocolate, lilac, cinnamon or fawn, and red to cream. You can have the genotype of a red or black cat examined in its DNA to check whether it carries dilution. You can examine the pedigree to check what can or cannot be inherited, and sometimes you can tell by looking at the offspring which traits the parents carry.
Black and red are dominant colours. Two cats that are homozygous for one of these colours, can never have kittens with a diluted colour. That is only possible if both parents carry the recessive dilution factor and pass it on. The other way around: two cats with diluted colours can never have kittens with a dominant colour. (a dominant colour will express itself when it is present in the genotype, even if only with one gene).

Tabbies.
Tabby cats are striped. There are several patterns:
-“mackerel”: thin stripes running parallel. What most people refer to as “tiger”.
– “classic tabby”: big, whirling patterns on the sides, like a marbled cake. In the UK this pattern is called “blotched”.
– “spotted”: these cats have spots on their sides, which can differ in size, and may look like the interrupted lines of a mackerel tabby.
-“ticked”, also called “Abyssinian” or “Agouti”. These cats don’t show stripes on their bodies, only in their faces.
The tabby pattern can occur in all colour combinations. You can determine which colour your tabby cat is by looking at the colour of the stripes and the tail tip, which are darker than their backgrounds. In cream or red kittens it is sometimes hard to define whether they are tabby or not. “Ghost markings” can be seen in young kittens, which later on disappear again.
A big help is, again, a little genetic knowledge, and the parents’ pedigrees. Tabby patterns are dominant. So a cat needs only one allele for tabby to be tabby. Every kitten that has one (or two) tabby parent(s), can be tabby. But: a kitten from two non-tabby parents can never be tabby.
Two tabby parents are no guarantee for tabby kittens, since the parents can both carry the non-tabby (“solid” or “self”) gene and pass them on to a kitten. Since non-agouti (the self or solid cats) can only express itself when melanine is involved, there is no optical (phenotypical) difference between cream/red kittens and cream tabby/red tabby kittens.

White.
White is a colour that is dominant towards all others. It covers them like a coat. White is called episthatic, because it represses all other colours.
A white cat with red eyes is called albino, it doesn’t have any pigment, so it doesn’t have any colour at all. There is a Siamese variant with blue eyes, though: a White Pointed cat, called Foreign White.
Often white cats, blue eyes or not, are deaf. There is a test for this: the BAER test. Deaf cats should be taken out of a breeding programme, and two white cats should not be mated to each other, because of the risk for deaf kittens. Sometimes a cat is only deaf in one ear.
In white cats the same rules apply as in the tabby pattern or the dominant colours red or black: because it is a dominant colour, a white cat has to have at least one white parent.
White cats carrying two alleles for white, will not be very common, because normally white cats are not allowed to mate each other. So most white cats carry a gene for another colour, which they got from one of their parents. Thus, it is very well possible for a white cat to produce a black kitten.
Statistically speaking, half of the kittens out of a white cat, are white.
A white cat’s eye colour can be blue, orange or “odd”; two different colours.
White kittens sometimes have black or grey spots or stripes on their heads, which later disappear.
Often breeders make a mistake when kittens are born white. All pointed kittens are born white, and get darker afterwards (see further down). So it is very important to know that two parents who are not white, cannot produce a white kitten.
In the Sphynx it is very difficult to determine which is a white, cream or cream & white kitten. Here, too, some genetics and the pedigrees can be a lot of help.
Cats with white spots have “…& white” on their pedigrees. These patches can differ in size, shape and place, and are named differently accordingly:
-“Mitted”: white paws.
-A “locket” is a small white spot on the chest.
-“Buttons” are white spots on the belly
-“Bi-colour” means that half of the cat’s coat or skin is white
-A “Harlequin” is white for the most part, with several large coloured patches.
-A “Van” is almost all white, with coloured markings on head and tail only.
– Sometimes a cat with white paws, chest and belly is called “tuxedo”. There may also be some white in the face.

Tortie.
This is what we call a cat with the colours black and red (or in the diluted version blue and cream, e.g.). These colours run into each other. The gene responsible for red (the O-gene) is located on the X-chromosome, so only females can be tortie. Tortie is also called tortoise.
When the different colours are easily discerned, and appear in larger patches, with white, the cat’s colour is called “Tri-colour” or “Calico”. These three-coloured cats are also always females. If and when a male tortie or tri-colour is born, it is usually sterile.
A tortie cat with stripes is called Torbie.
Also interesting: if a red or cream stud is mated to a queen with a different colour from red or cream, all female kittens will always be torties.

Siamese, Tonkinese, Burmese.
These are often called colours but are in fact patterns, and are the result of a series of alleles that determine albinism with lesser or stronger effects. Siamese are coloured almost white, except for the “points” or extremities: nose, ears, tail and paws. Tonkinese cats are a bit darker, and Burmese are the darkest of the three. All three have darker points than the rest of their bodies. Temperatures have a big influence on these cats, though: Siamese allowed to go outside, will have a much darker body than that of Siamese who stay indoors. That is why Siamese kittens are always born white: in the womb the extremities are as warm as the rest of the body, whereas in the outside air, after birth, the extremities grow a bit colder than the rump, which houses the vital organs that are kept warmer by blood circulation.
A Siamese cat is also called Colour Point (or simply Point).
A Tonkinese cat also has a different name: Mink.
And a Burmese cat ca also be called Sepia.
All these forms can affect all colours. E.g., a Red Point is a red cat with Siamese properties. A Chocolate Mink is a brown cat with Tonkinese properties. A Blue Sepia is a grey cat with Burmese properties .
How can you see whether a kitten is Siamese, Tonkinese or Burmese?
Siamese kittens are born milky white and get their colours later. In dominant colours it is more obvious than in diluted colours. Minks and Sepia’s are born with colour, and those colours will get darker later, as well.
A second give-away is the eye-colour. All kittens are born with blue eyes, just like human babies. A cat’s eye colour starts changing around the age of 10 weeks.
Siamese cats have blue eyes. Tonkinese cats have blue-green eyes, also called aqua. Burmese cats have yellow eyes. The problem is that often the difference between blue and aqua only gets clear after several months. Before then pedigrees are made, so breeders have to know for sure.
Here, too, some genetics and the parents’ pedigrees can be of help:
A Siamese cat needs two genes for Siamese. So does a Burmese cat. When a Siamese cat is mated to a Burmese, the result is a Tonkinese.
Two parents who are Siamese can only have Siamese kittens. Same with Burmese. The kittens of two Tonkinese, however, can be either Siamese, Burmese, or Tonkinese, depending on the genes that are passed on and combined. A cat cannot be “carrier” of the Tonkinese gene, because you need the combination of both Siamese and Burmese. A kitten from a Tonkinese parent can carry the gene for either Siamese or Burmese.

A cat carrying no single pointed gene at all, can never produce a pointed kitten or a Mink kitten. In combination with the right partner, it can produce kittens that carry either the Siamese or the Sepia gene. A kitten carrying only one of either genes (Siamese or Sepia) will not show this on the outside (fenotype) It could, in combination with the right partner and depending on which gene it carries, produce Siamese, Mink or Sepia kittens.
So it is important to look at the pedigree at former generations. Sometimes you can find out by studying the pedigree which genes can or cannot be passed on.
It becomes more difficult when a cat is Siamese or Burmese carrier, but isn’t Siamese or Burmese itself, especially if this trait had been passed on for a few generations without surfacing. Two non-pointed parents can get pointed kittens, if they both carry and pass on the gene. It is, therefore, a recessive gene.
As kittens grow older, often the colour of their nose leather and paw pads can tell you what colour their coat or skin is.

Prediction of kittens born with Point markings:

EMS-codes.
EMS is short for “Easy Mind System” and has been developed to allow breeders all over the world to use a universal code for the colours of their cats and kittens. In this code you can find letters and numbers determining coat colour, patterns, eye colour, the breed’s name, gender and ear- or tail shapes. These codes are also to be found on pedigrees. A website where you can find the EMS table, and lots more information about breeds, genetics, diseases and pedigrees is: www.pawpeds.com

For those whose appetite is triggered: Pawpeds is a good place to start learning about feline genetics. On Zooclub there is a page where you can find colours of nose leather and paw pads for each coat colour.

What follows is a scheme in which you can find all possible colours of kittens, if you know the colours of both parents. Dilute colours are also mentioned, but they can only occur if both parents with non-diluted colours carry and pass on the dilute genes to a kitten.

First a reminder for the ems codes, which you can also find in the chart:

a = blue
b = chocolate (brown)
c = lilac
d = red
e = cream
f = black tortie
g = blue cream tortie
h = chocolate tortie
j = lilac tortie
m = caramel
n = black (= seal in pointed cats, which have a very light colour except for the extremities. They are genetically black)
o = cinnamon
p = fawn
q = cinnamon tortie
r = fawn tortie
s = silver/smoke
t = amber (yellow)
w = white
x = unrecognized colour
y = golden

colour predictions for a Seal or Black father, Blue father, Chocolate father

colour predictions for a Lilac father, Red father, Cream father

Colour Pattern Prediction for Pointed cats:

Colourpoint x colourpoint: all kittens are colourpoints. They are all born white and their eyes remain blue.
Colourpoint x mink: 50% colourpoint and 50% mink kittens. Mink kittens are born with colour, which darkens more with time. Their eyes turn aqua.
mink x mink: 25% sepia kittens, 50% mink kittens and 25% colourpoint kittens. Sepia kittens are born with colour, their eyes turn yellow(-greenish).
mink x sepia: 50% mink and 50% sepia kittens.
sepia x colourpoint: all kittens are mink.