Genetics is of interest to anyone who likes rats whether they are new-to-rats through to those more established. One of the things that takes people by surprise when they first come to rat shows is the number of distinctive varieties and how they come about. A little later, when owners consider breeding their rats, especially for the first time, it is natural to wonder what might result (and plan accordingly). Then after a while, it will be necessary to prevent inbreeding and an outcross will be needed. It is also fair to say that anyone who has bred a few litters is likely to have had something unexpected pop up. Genetics can help to explain all of these.

I cannot hope to give anything other than a simple overview into the mechanics of how rat genetics work. The idea is that these few pages will be easy to follow, help prevent commonly made mistakes and provide a stepping stone to the heavy duty stuff should you ever need it.

The first and most obvious thing to know is that rats inherit their characteristics from their parents. That means a boy rat and girl rat will always produce baby rats. Never cats, dogs, frogs or mice. In looking at the differences between the wide variety of rats, it is too easy to forget the even wider range of things that rats have in common, all of which are inherited from mum and dad.

In addition to being a rat, the kitten will also inherit certain characteristics peculiar to its parents. This is the bit that we are really interested in. Most of us know that mum rat and dad rat will have baby rats, the question is which varieties! This is the question that genetics aims to answer.

Genetics is the study of genes. A gene is a theoretical unit of information that determines a simple characteristic in a living creature. In rats, a single gene would control dumbo ears or eye colour. The gene idea has been around since the 1850s. More recently, studies have found the physical means by which this information is carried. It's in this context you may have heard about chromosomes, DNA and the famous double helix, but to keep this simple I'll stick with genes. At a very basic level, a simple characteristic is determined by a single gene. More complex characteristics are controlled by a group of genes. In rats, fur colour is determined by a group of genes. That said, we can look at the individual genes responsible in turn and see how the combined effect occurs. On the next page, we will start with one gene at once, and work our way up.