English: Watercolor diagram of recessive epistasis in golden retrievers' coat coloring. Chocolate is a recessive color while black is dominant (represented by the black and brown rectangles). A second gene determines if there is pigment at all (represented by the yellow and black triangles). Having one functional copy will produce pigment (denoted by the black triangle), but inheriting none will yield a golden dog (denoted by the yellow triangles). Had the offspring got even one copy of pigment production from either parents, this would have been a chocolate lab.