Golden gave birth to a black dog

The reason why the golden will give birth to black puppies is mainly because the genes are impure, respectively, in two cases: 1. and it may be mated with other breeds of black. 2. the ancestral lineage of the golden is impure, because the genes are inherited from generation to generation, so if two are golden golden, but the birth of black puppies, it is likely because their ancestors were once impure, only the black hair happens to be recessive The gene is revealed in this generation.