Minor genes of major importance.

In genetics literature, modifiers are described as genes “of minor importance”. For a fancy mouse breeder, they are quite important. While the major genes produce the desired colour, coat and markings as such, the modifiers produce the desired shade, quality of coat and the exact markings.

It is rather easy to get a, say, Blue mouse. Getting the right shade of blue on a Blue mouse is difficult. The same goes for practically all mouse colours, markings and coats. In order to get the exact shade, the desired amount and distribution of white on marked varieties and the desired length and/or curliness on coated varieties (as well as good short coat on a short hair mouse), the breeder will have to tackle with modifiers.

A good breeder needs to develop her eye for mice to be able to build the right modifiers to her strain of mice and to get rid of wrong ones. After all, the finer points of breeding involve exactly doing that. While a good understanding of genetics helps to get the right colours, it also helps in understanding the admittedly difficult and unstudied actions of modifying genes.

Studying pictures of good - and bad! - examples of all the different mouse varieties is a good thing. However, nothing beats first-hand experience of seeing mice live in shows, judged by a qualified, experienced standard class judge. Volunteering as a show secretary or assistant gives you a great opportunity of seeing show mice and hearing judges' opinions on them. Working at a pet show is another option, but only as an opportunity of seeing different kinds of mice. However, as pet shows are about good mouse husbandry and how healthy and tractable the mice are, these shows and pet show results do not tell anything about how good any given mouse is when it comes to the standards.