* Inhibitor is the gene that suppresses the development of pigment in the hair of the coat. Cats like smokes and chinchilla have this inhibitor gene (I).

olygenic nheritance

See an old picture of one of the first persians. Comparing the persians from the early days with the persians from now, is looking at the effect of polygenes. The type of heredity described in the other genetics pages is known as discrete or discontinuous because the characteristics involved are sharply defined. No one will confuse a red cat with a black cat, or a shorthair cat with a longhair. Yet not all variations are of this nature!

Many characteristics can vary continuously from one extreme to another. The blue cat is a nice example, the coat of a blue cat must be light blue, but there are blue cats however that have a dark blue color. All variations between light blue and dark blue are possible. This phenomenon is caused by polygenes. Polygenes are large groups of genes located at different locations and even at different chromosomes; they effect the same characteristic.

Black cats need to be as dark as possible and there are some polygenes that are the positive polygenes for a black cat; the same genes are the negative polygenes for a blue cat. Based on this theory it wouldn't be wise to make combinations between blue cats and black cats.

Sometimes polygenes are hidden. A tabby for example, the genes A, T, Ta,tb, and sometimes the O gene, will make the cat look like a tabby. Polygenes are involved to make a strong and bright tabby pattern. All cats carry these polygenes while many will not show the effect because they are no tabby.

How to use the theory of polygenic inheritance? Lets assume you want to improve a particular characteristic on your cats. There are two ways:
1. you can use the cats in your cattery and by every improvement on a kitten you can use the kitten for your future breeding program. This is a good method but sometimes it will take a couple of years.
2. The other way is to use a cat from an other cattery, a cat that has an extreme high quality on this particular characteristic. This is in most cases the best and fastest way.

The problem is that there are so many different characteristics depending on polygenes; some cats have an extreme high quality on one characteristic, and poor quality on an other which means that sometimes you have to take a step back on one quality to accomplish an improvement on the other.

You also need a bit of good luck...