About This Page
Finding out what genes your cat has that create his or her unique look is a subject that interests a lot of people who may not have the time to look up the genetics for themselves. This page will allow them to go step by step through the process of matching the features of their cat to the genes that produce those features.
The links on this page will jump to pages with more description and with sections on how to fill out the gene table accordingly. Navigate using links instead of reading the other pages from front to back.
The Gene Map
This map shows the major genes involved in determining cat coat color. I’ve created a blank form on this page to be printed or copied onto paper for the analysis.
Each Locus gets a separate line on the table, each of which has two genes. One is passed from the father, the other from the mother. Dominant genes have their full effect if one is present in the pair, recessives require both to be the same. Some genes have a mixed effect when paired with another, rather than pure dominance.
If there are more than two gene options for a Locus, there will be a ‘power ranking’ where Gene A dominates everyone, Gene B dominates all but A, down to Gene E which is recessive to all above it. The majority of the genes for cat coat just have two options.
Hair length is the length of the hairs on the coat. ‘Bald’ cats are controlled by other genes.
Go to Hair Length…
White on cats is not a color, but is what remains when normal color is blocked by the action of another gene. The amount can vary from small spots to the entire cat. After determining the cause of the white, we can move on, ignoring the white areas.
If your cat has no white markings, Go to “Cats with no White”
“Pointing” refers to a pattern where the color of the cat changes with position on the cat. Pointed cats are darker on the face and ears, feet and tail than they are on the body. The most well-known example is the Siamese.
A problem that the pointing gene gives is that it modifies the color everywhere, complicating the color determination we make later. The cat on the right is genetically black, even if the fur is dark brown, light browns and cremes.
There are actually three different kinds of pointing patterns, controlled by two genes on the Albino Locus.
If your cat is not pointed, Go to “Non-Pointed Cats”.
Genetically, all cats are tabbies, in that they all have a gene that provides a tabby, or striped, coat. The pattern can be prevented from displaying by other genes, such as the various “white” genes. The pattern itself is made by a combination of regular, solid hairs on a background of ‘agouti’ hairs. On these hairs the color is laid out in bands with the ‘base’ color of the hair showing between. This makes the hair lighter overall, with a shimmering effect as light and dark bands are exposed and hidden again. Presumably this is a good camouflage pattern, serving to break up the outline of the cat when hiding or stalking prey.
A ‘solid’ cat is made by a second gene, that ‘paints over’ the agouti hairs with the main color. This overpainting only functions for black-pigmented cats. Orange cats will always show the stripes, and even black cats will often show ‘ghost stripes’ in certain lights and angles.
If your cat is not showing a tabby pattern, Go to “Solid Cats”.
After isolating out the coat patterns, we are left with actual colors of a cat’s coat. There is one general color modifier gene, “Dilution”, that affects both colors in tandem. After that, we can get down to deciding the color genes themselves.
The “Dilute” gene does not affect the pigment of a cat itself, but changes how the grains are laid out. Instead of being evenly spread, the grains are clustered together with spaces between. Dilute Black becomes a silvery blue grey color tagged as “blue”, while Orange becomes a creme color. For a tabby, use the color of the stripes to check if a greyish cat is dilute – a grey tabby that has black stripes on a grey background is a black tabby with low rufousing, not dilute.
If your cat is not dilute, Go to “Dense Pigment Cats”.
Orange is one of the two pigments that cats have. The Orange gene is located on the sex chromosome, so there are some interesting effects. The Orange gene has two options. The dominant ‘O’ gene replaces black pigment with an orange pigment. The recessive ‘o’ option allows black to show. Because the locus is on the X chromosome, females that have two X’s randomly choose one to use during development, so if they have an O/o mix parts of the fur will be black and parts will be orange, forming a tortoiseshell or calico cat.
All cats, even those that show no black color, have a gene to control the black pigment. The pigment remains the same, but the variants lay out the pigments in grains of differing shapes, which changes the apparent color of the hairs. “Black” hairs have nearly round grains, and “Chocolate” and “Cinnamon” grains are progressively more oval. These alternate colorings are not very common, and are recessive to the normal Black option.
These genes change the way the color is laid out on the individual hairs. They make a major difference in the appearance of the cat. If your cat does not seem to fit the other categories, you can check this section out. Except in purebred cats, these are rare genes.
The combination of these two genes produces Smokes, Shaded Silver, Shaded Golden, and Chinchilla cats. The standard color is reduced to a smaller fraction of each hair, from mostly colored to mostly uncolored except for the tip.
I don’t plan to add any of these genes at present, as they tend to be one gene per trait. Examples of this are the Scottish fold ear gene, the various hairless genes, the various kinky fur and curled fur genes, and so on.