The difference between cat breeds isn’t quite as vast as that of dogs but many cat breeds have unusual features that make them unique. This may be curled ears, short legs or unusual fur. Most of the cats arose from a spontaneous mutation and were developed to create new cat breeds.
New breeds which arise from spontaneous mutations take years to develop, breeders must determine if the mutation is dominant or recessive and if it causes any long-term effects on the cat. Established breeds or domestic (mixed-breed) cats are often utilised in order to increase the size of the gene pool.
Dominant vs recessive genes
Cats acquire two copies of each gene, one from the mother and one from the father. A dominant gene only needs one copy for the trait to be expressed, whereas two copies of the recessive gene must be inherited to be expressed.
Some cats may inherit one dominant and one recessive gene, the dominant gene overrides the recessive, which is not expressed. However, if the cat mates with another cat who also carries the same recessive gene and the kitten receive a copy from each parent, the trait will be expressed. This is known as a carrier.
In some cases, a doubling up of a dominant gene (homozygous) is lethal.