* Genetics: Dog coat color is determined by multiple genes. The most common gene involved is the "E" locus. A dog needs at least one copy of the "E" allele to produce black pigment. Red dogs typically have two copies of the "e" allele, which prevents black pigment production.
* Recessive genes: It's possible for a dog to carry a recessive gene for black coat color even if they don't express it themselves. However, for a black puppy to be born, both parents would need to carry this recessive gene. Since red dogs usually don't carry the "E" allele, this scenario is very improbable.
Exceptions:
While extremely rare, there are a few exceptions:
* Mutations: A spontaneous mutation could occur, introducing the "E" allele into the offspring's genetic makeup. This is incredibly rare.
* Hidden ancestry: If one of the red dogs has a hidden black ancestor further back in its lineage, they could carry the recessive "E" allele, making a black puppy possible.
Bottom line: While not impossible, it's highly unlikely for two red dogs to produce a black puppy. The odds are heavily stacked against it due to how coat color genetics work in dogs.