Odds of a Pure Black Cat in a Litter

When two cats mate and produce a litter of kittens, each of those little ones receives half of his genetic makeup, in the form of chromosomes, from each parent. These 19 pairs of chromosomes contain DNA molecules made up of genes, according to the University of California, Berkeley. A kitten gets two pairs of genes from each parent. These genes determine your kitty's temperament, coat color, coat length, eye color and other physical characteristics. Depending on how these genes combine, your kitty could produce a pure black kitten, but only if each parent carries the genes necessary to produce one, according to the Cat Fanciers' Association.

Some genes determine which traits, like his coat color, that a kitten will have when he's born. These are known as dominant genes. Recessive genes don't appear among his physical characteristics but are carried in his genetic code and can affect his offspring. The gene for a black coat color is a dominant gene and controls the production of eumelanin by the kitty's body, which is the pigment that makes his fur black, according to Catster. If either parent carries this gene, then one or more of the babies will be black. Usually, if one of the parents is pure black, this means that she is a carrier of this gene and it's likely that one of her offspring will be too.

There are three basic gene combinations that govern each of your kitty's traits. Those are "BB," meaning two dominant genes, "Bb" meaning a dominant and recessive gene and "bb," meaning two recessive genes, according to the Tech Museum of Innovation. When black cats with "BB" genes, representing the dominant gene combination resulting in a pure black coat, get together, all of their offspring will be black, even if only one parent has this combination. When two black cats with "Bb" genes mate, odds are three to one that their offspring will be black. If one kitty who isn't black has the recessive black "bb" genes and is bred to a "Bb" cat who is, their offspring have a 50-50 chance of being black.

If you don't know what the genetic background is for your expectant mama kitty or her paramour, then there is no way to determine the chances of her giving birth to a black kitten unless she is pure black. Cat genetics can get even more complicated because our feline friends may become pregnant by more than one father at the same time, according to Dr. Jeff Nichol's website. This means that only the mother's genes can reliably give you an idea of her kittens' coat colors, unless she's been kept indoors during her heat cycle. Keep in mind that other genes may also affect the appearance of a kitten's coat, including those that establish his coat patterns.