Mom and dad contribute equally. There are three types a gene can be, dominant vs. resessive, codominant, and incompletley dominant. All pups get one copy of the gene for each allele from each parent. Most colors work on dom vs. recessive, where the dominant will mask any recessive, but a dog that is the dominant color could carry the resessive, so you could get a pup that is a recessive color out of two dominantly colored parents. Codominant is when both genes for the particular allele are shown, and incompletley dominant is like the cremello gene in horses, one copy will act on the color, in this case, diluting it down.