First a little about genetics to help you understand how color is or isn't inherited. Please Note I am not an expert on genetics and this is not my work, this work is credited to Chris Davis and comes from what I have learned from reading the article "whats in a color" which I found on the internet, unfortunately I could not find the link again to use the article in depth so am using excerpts from the article that I hope you will find useful.
Inheritance:
On a simplified scale...
Recessive:
If a genetic trait is recessive, a dog needs to inherit two copies of the gene for the trait to be expressed, or seen. Therefore, both parents must be carriers of a recessive gene in order for an offspring to express or show that genetic trait. If both parents are carriers, then there would be a 25% chance that, that offspring would express that trait.
Double Recessive:
If a dog expresses a color known to be recessive, then they inherited the gene from both parents making it double recessive and if that dog is bred to another dog that also expresses the same recessive color then that color will always “breed true”, meaning they will only produce puppies of that same color. For example a Black & Silver (double recessive) bred to same will only have Black & Silver puppies because the only genes the parents can contribute are Black & Silver. The recessive genes will always “mask” or override dominant genes when inherited from both parents.
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Dominant:
If a genetic trait is dominant in a dog it only needs to inherit one copy of the gene for the trait to be expressed. The dominate gene can be “masked” by the doubling of recessive genes. For example, all Mini Schnauzers carry the genes to be Salt & Pepper but if they inherit the genes to be White from both parents, the Salt & Pepper is covered or “hidden” and the dog’s coat will be White.
Simple Dominant:
This means that if one gene is present it will manifest fully, and if two are present it manifests no differently than with one. for Example take a Salt and Pepper Female with no White gene carried bred to a White male. Since she has no White gene and he had a masked Salt and Pepper gene, the resulting puppies will all be Salt and Peppers ( the puppies however will also all carry for the white gene as well ), providing however no other matching recessive genes are carried or passed on by either of the parents.
Dominant Direct Inheritance:
Genes that are dominant direct inheritance cannot be "hidden" or “carried”. They must be directly inherited from a parent. They cannot “skip” a generation. An example is a puppy that is “One Color” one of the parents must also be “One Color” (not necessarily the same base color).
Homozygous:
Homozygous means that they have doubled up dominant genes thus ensuring they can produce no other color. For example homozygous “One Color” Black, meaning all puppies from this dog will be Black. One cannot ensure “One Color” Chocolate because brown-base is itself recessive, thus requiring the brown-base recessive gene from both parents, recessive genes cannot be homozygous. In order for a pup to be homozygous for a color, both of the homozygous dog’s parents have to be that color, but the flipside is not true…just because both of a dog’s parents are Black, it does not necessarily make the dog homozygous. The exception to this is if the dog’s parents are both homozygous themselves, then all their offspring must be homozygous.
Heterozygous:
Heterozygous is the opposite of homozygous. It means that the dominant gene is not doubled up and the dog is carrying “hidden” or recessive gene(s), which can be expressed in the proper mating.
To further complicate matters, the various color genes, called alleles are carried on a DNA strand in specific spots called Locus (plural loci) like notches on a stick. So this means that one dog can have several different “notches” on their DNA stick and it is not just a matter of whether they have this gene and not that one, but also how the different genes affect one another. For example, let’s say we have a Black dog that is heterozygous for the color black (K) genetically on the DNA strand and also not black (k) on the DNA stick..So our Heterozygous Black dog is Kk at the locus or “notch” for black. Bred to another heterozygous Black,
so obviously the possible combinations are 25% homozygous Black, 50% heterozygous Black and 25% not Black. So if the dog is not Black, what color is it? This is where the other “notches” come into play. The dog will have other genes to determine what color they will be when they are not another color.
It appears however, as though all Mini Schnauzers carry for Salt & Pepper and that it can be masked or hidden by other genes, and when the other genes fail to be expressed, then the S&P gene fulfills the need.
