A "mismating" is when a female of one breed has an unplanned mating with a male of another breed. A "double mating" is when a female manages to mate with two stud cats a few days apart. In double matings, the studs may be different breeds or different colours and the only evidence of the double mating might be when unexpected traits pop up in kittens one or two generations later.

Although breeders are careful to control who mates with whom, both sexes can be very resourceful, exploiting any lapse in security to reach each other when the female is in oestrus. Some females are also “silent callers” while others return from their assigned mate still ovulating and manage a tryst with a male that was supposedly sexually immature.

The question of what happens next depends on the ethics of the breeder. Reputable breeders, when faced with kittens of dubious parentage (“love kittens?), admit to a “whoops mating,” home the kittens accordingly and review their security measures. Some breeders will be genuinely unaware of a mis-mating because the kittens are exactly as expected. There are undoubtedly a few breeders willing to register such kittens with false pedigrees and no-one is any the wiser until unexpected colours and traits emerge several generations down the line. In a similar way, kittens born of test-matings sometimes found their way back into the gene pool of one or other parent breed. The recessive Cornish Rex gene found its way into the Persian gene pool by this means. It’s unknown how widespread it is, but sometimes rexed Persians occur and sometimes rex turns up unexpectedly in other breeds that contain Persian blood. Ironically, it’s the breeder who has unexpectedly curl-coated kittens who might be accused of a mis-mating.

One of the most famous mismatings resulted in the Burmilla breed. A poorly latched interior door allowed a Burmese and Chinchilla Persian to get together, producing kittens so pretty that the mating was repeated and breed was founded. The Bombay, a solid black Burmese type cat, was once alleged to have been the result of a mis-mating.

Many years ago, a breeder obtained a Balinese male whose sire came from a cattery that bred both Balinese and British Shorthairs. He looked 100% Balinese with very good type, but when bred to an unrelated solid blue female Oriental, he sired a kitten that resembled a longhaired version of a British Blue Shorthair. The coat texture and density was quite different from an Oriental Longhair. British Shorthair breeders did a double take when they saw photos of the offspring. Both the kitten and its sire were neutered and the mother, when mated to other studs, never produced another kitten like it. Did that Balinese male have some British Shorthair ancestry, perhaps from a dual mating? Did its sire produce other progeny that could one day meet up and produce kittens with unexpected traits? In the long run this becomes largely academic as breeders consistently select for conformation and fur type and any putative British Shorthair influence would be selected against. Unlike rexed fur in Persians, there are unlikely to be any real surprised further down the line.

An accidental breeding of American Wirehair and Oriental Longhair produced a longhaired wirehair with vaguely Oriental conformation.

One person’s legitimate outcross is another person’s mismating. In various Europe registries, Singapuras may be outcrossed to Abyssinians, Burmese, Korat and black Domestic Shorthair. In most American registries these would be considered a deliberate mismatings! One Australian cattery states quite clearly that they will not sell any Singapura cats or kittens to breeders involved in any Singapura outcross programme.

Another source of unexpected results, that can lead to later accusations of mis-matings, are breeders who mis-register their cats through lack of understanding or a refusal to conform to convention. For example, a non-exhibiting breeder of British Shorthairs has some highly suspect pedigrees. Cats that are dominant white are registered either as “van bicolour” (mistaking the temporary “kitten cap” for van or harlequin markings) or as the masked colour (as though dominant white was not there at all). The registered pedigrees are therefore false because they don’t reflect the actual colour of the cats. This causes errors in pedigree databases that can persist for several generations and can lead to accusations of mis-mating because two non-white cats (according to their pedigrees) cannot produce solid white offspring that breed as dominant white.

A “kitten cap” is a small smudge of colour that is found on the top of the head of many dominant white gene kittens. It reflects the colour being masked by dominant white and it is only present for 8 – 12 months. It is not a “van” marking. Van pattern cats are due to a different gene – the white spotting gene – and have a coloured tail and permanent, distinct markings between the ears. A cat wrongly registered as “van pattern” on the basis of a kitten cap will not breed as a van, it will breed as solid white. Any breeder who describes a solid white cat as an “odd eyed full reverse black bicolour carrying chocolate” has no grasp of colour genetics or nomenclature – there’s no such thing as “reverse bicolour” and if a solid white cat cannot be a bicolour. A kitten cap does not make a cat bicolour.