How coat color inheritance works in cats

Genes come in pairs

Every cat carries two copies of each coat gene – one from its mother, one from its father. Some versions of a gene (alleles) are dominant: a single copy is enough to show. Others are recessive: they only show when a cat inherits them from both parents.

That is the key to breeding surprises. A recessive gene can travel invisibly through generations of carriers – until two carriers meet and a kitten inherits it twice.

Black, chocolate, cinnamon – the B series

The base pigment gene comes in three versions: full black pigment (dominant), chocolate, and the rare cinnamon. A cat with at least one dominant allele shows full dark pigment. Only a cat with two chocolate alleles is chocolate – and only two cinnamon alleles make cinnamon, which is why the color is so prized among breeders.

Dilution – how blue and lilac happen

A separate gene decides whether pigment granules are packed densely or loosely in the hair. Two copies of the recessive dilution allele soften every color: black becomes blue-grey, chocolate becomes lilac, cinnamon becomes fawn. The famous blue coat of the Chartreux and “blue” Ragdolls both come from this single mechanism.

The orange gene and why torties are female

The orange gene sits on the X chromosome. Males have one X, so they are either orange or not. Females have two – and if one carries orange while the other does not, both programs run at once, patch by patch. The result is the tortoiseshell: a mosaic of orange and dark that is almost exclusively female.

Tabby stripes and colorpoints

Every cat actually carries a tabby pattern – but the agouti gene decides whether you see it. A dominant agouti allele lets the stripes show; two recessive copies produce a solid coat with the pattern hidden underneath.

Colorpoint cats – like Siamese and Ragdolls – add a temperature trick: their pigment gene works best in cooler skin, so color concentrates on the ears, face, paws and tail.

From theory to practice

Real breeders use these rules every day: predicting litters, tracking carriers, planning pairings several generations ahead. It is equal parts science and detective work – and it is exactly the system we modeled in our browser game, where every kitten is born from real allele inheritance rather than a random color picker.