Do Cats Inbreed?

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Fact checked by  Dr. Lizzie Youens BSc (Hons) BVSc MRCVS
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Four cute kittens

Most responsible pet parents will be aware that when you own a male and a female cat you will need to neuter at least one of them to prevent a litter of kittens (and another, and another!). But, what if the male and female cats are brother and sister, mother and son, or father and daughter? Does that matter?

Key Takeaways

Any male and female cat will breed if the female is in season, and neither are neutered.

Cats have a high drive to reproduce and do not comprehend the taboo or health concerns associated with incest and inbreeding.

The only permanent way to prevent your male and female cats from reproducing is through neutering.

Are you safe from being inundated with litters of kittens then? Let’s find out about inbreeding in cats and the health concerns it can cause.

Do Cats Naturally Inbreed?

It might seem shocking, but cats will naturally inbreed if given the opportunity. This means that, if a male cat is around when his daughter is in season, they will breed. Similarly, if litter mates grow up together and are unneutered, they will breed together if they have contact while the female is in season. Even stray cats and wild cats will inbreed if they happen to be around relatives when they are in heat.

Why Do Cats Inbreed?

Cats have a high drive to reproduce, and they are very opportunistic breeders. If an unneutered male, close relative or not, is around a female cat in heat, they will mate. In fact, did you know that a female cat can carry a litter of kittens where there are multiple different fathers?

Female cats are induced ovulators, meaning that they release eggs from the ovary as a response to mating, which can happen multiple times during one season.

Of course, in the wild, while there is an element of inbreeding, there is usually a large enough population that the rates of inbreeding are relatively low. On the other hand, breeders of pedigree cat breeds may use selective and controlled inbreeding to create positive breed traits in the offspring. However, responsible cat breeders will not breed from very closely related cats.

What Happens When a Brother and Sister Cat Mate?

Two cute ginger kittens

Sibling cats will readily mate with each other, but the resulting litters have an increased likelihood of genetic abnormalities.

You might be appalled to think that a brother and sister cat would mate, but they would. Remember, incest is a human concept, and cats don’t have these social rules or any understanding of the potential genetic concerns. Therefore, if a brother and sister cat, or any other pair of related cats, the resultant pregnancy will often proceed like any other pregnancy.

However, the limited gene pool caused by inbreeding can make it more likely that the pregnancy will be lost or the litter of kittens will have health problems, genetic defects, or physical abnormalities. If you are concerned that your female cat might be pregnant after mating with her brother, read our article here about how to tell if your cat is pregnant, and speak to your veterinarian.

Do Inbred Cats Live Longer?

Inbred cats do not live longer than non-inbred cats. In fact, in many cases the opposite is true, and the lifespan of an inbred cat might be much less. Breeding two related cats means a more limited gene pool, with an increased risk of mutations.

This can mean more desired aesthetic traits, like particular colorings, face shapes, and stature, but it also means more likelihood of genetic abnormalities and an increased risk of health issues. Therefore, breeders of purebred cats have to use selective breeding to balance maintaining the bloodline and breed standard while reducing the effects of inbreeding.

What Are the Health Concerns Associated With Inbreeding?

The offspring from inbred cats could develop a variety of health conditions or abnormalities as a consequence. This could be a relatively benign deformity, like an extra toe or two – which may need nails clipping more often but rarely becomes a problem. This is known as polydactyly and is common in inbred cats. In fact, some polydactyl cats have as many as 8 or 9 digits per paw.

Equally, inbred kittens may be more likely to have misaligned jaws, making it more difficult for them to feed from their mother or eat food as they grow. However, consider an even more concerning consequence – if the family line carries a genetic predisposition for a health condition, like cardiomyopathy, for example, the chances of the offspring of two parents from that family line developing the condition will be higher.

How Do You Prevent Inbreeding in Cats?

If you have a male and female cat who are related and aren’t neutered, the only reliable and permanent way to prevent inbreeding is to get the female spayed or the male neutered, or both. Until you have arranged the neutering procedures at your veterinary clinic, you should keep them strictly separate while the female is in heat, and be aware that following neutering, the male will remain fertile for four to six weeks.

Female cats may come into season during the Spring or Summer of their first year of age, meaning that the age at which they come into season is quite variable. Similarly, the age at which a male kitten becomes fertile is not exact but may be from as early as six months of age.

Therefore, you might consider early neutering if you have a male and female kitten. You can find out more here: Early age spaying and neutering of cats.

Why Else Should You Neuter Your Cat?

Cat with collar

If you own multiple cats of different sexes, it is advised to get them surgically neutered if you don’t wish to breed them.

Of course, preventing a succession of unwanted pregnancies isn’t the only reason to get your furry family members neutered. Neutering will prevent their compulsion to mate, meaning no more yowling and frantic attempts to escape, or the necessity of keeping your female cat inside during a season.

Neutering can also prevent the spread of viral infections, including feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV), and, if you have an outdoor cat, it might help reduce fighting and roaming. If you’re wondering about the costs of neutering your cat or kitten, read How much does it Cost to Spay or Neuter a Cat?


Inbreeding in cats occurs both naturally in the wild and during breeding programs. However, responsible cat breeders are careful to prevent breeding between cats that are too closely related, in order to keep the gene pool as broad as possible, improve genetic diversity, and prevent health consequences.

If you have two cats of different sexes who are related, it’s very important to neuter them to prevent inbreeding, as cats aren’t affected by the social taboo of incest.

Also Read: Can You Clone A Cat? Costs, Procedures, & Ethics

Frequently Asked Questions

Do cats breed with their own family?

Cats will breed with their own family if the female is in heat and the male is around. The concept of incest is not understood by cats, who have a high drive to reproduce.

What happens if cats mate from the same litter?

If cats from the same litter mate, there is a higher chance of genetic health conditions and extra digits (polydactyly).

Do stray cats inbreed?

Stray cats, like owned cats, will breed spontaneously with cats of the opposite sex if they happen to be in season.

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About Dr. Hannah Godfrey BVETMED MRCVS

Hannah graduated from the Royal Veterinary College, UK in 2011 and began work straight away at a busy mixed practice. Initially, she treated all species, but as the small animal hospital became busier, she focussed on small animals. Hannah is an expert on cat behavior and nutrition.

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