Whereas a black cat can be a carrier of chocolate or cinnamon, but not both.īoth red and black can be affected by the dilution gene. Cinnamon is absolutely recessive and a cat of a cinnamon phenotype must be of the genotype ‘b1b1’ - if he carried either chocolate or black, he would not be cinnamon in colour.Chocolate is recessive to black but dominant over cinnamon.The first mutation of the black gene created chocolate, which is written as ‘b’ and the second mutation of the black gene created cinnamon, which is written as ‘b1’.

The black gene has mutated over the years. Every other colour and pattern is a variation on one of these two original colours. Red or black?Īll British Shorthair cats are either red or black. So black is a capital b - B, and chocolate is a small b - b. The wild type is always written as a capital letter as it is the dominant type. Black would be the wild type, as would shorthaired. The wild type of the gene is the dominant type - this is the gene that would dominate in the wild. heterozygous = each chromosome is different (so the cat could be black carrying chocolate, or shorthaired carrying longhair).homozygous = both chromosomes are the same.The chocolate gene is said to be recessive because, unless there are two chocolate genes, the cat will not be chocolate.

The black gene is called the dominant gene because it will always manifest itself if a cat has one chromosome coding for black. Where this occurs the cats phenotype is said to be black, because its appearance is black, but its genotype is heterozygous for black and chocolate because it has one chromosome that codes for black and one that codes for chocolate. black, but also be a carrier of another colour, like chocolate. This is how it is possible for an animal to be one colour, i.e. Genetics in all animals are governed by chromosomes. Many of the principles and outcomes are equally applicable to most other breeds as well.

Since we are registered breeders of British Shorthair kittens and cats, this article will focus exclusively on British Shorthair colour genetics.

Blue tabby shorthair