Do Sibling Cats Mate With Each Other?

man holding a group of sibling kittens

Have you ever heard about the story of Zeus and Hera? In Greek mythology, Zeus was a god and he grew fond of his own sister, Hera. He turned himself into a sick bird to gain her sympathy.

When Hera took the bird in her care, Zeus changed back to his human form and ravished her. Thankfully we mere mortals don’t have the ability to shapeshift.

When it comes to cats, do sibling cats mate with each other? It is common for cats to mate with their own siblings and even parents. Cats reach sexual maturity at a young age and when a female signals her readiness to reproduce, her male sibling will be led by his feline instinct to mate with her.

Such behavior might strike us as somewhat revolting but it is very commonplace in the animal kingdom. However, that doesn’t mean that it is healthy for cats of the same litter to engage in incestuous mating.

Let’s take a deeper at the problems that can arise from closely related cats mating and what you can do about it.

Do Cats Know They Are Siblings?

As humans, we do have the ability to recognize and understand who we are closely related to like our own family members. Our body has a natural defense mechanism to stop inbreeding from happening.

Some might say that cats from the same litter mate because they don’t form this bind and recognition as humans do.

That isn’t entirely true.

When kittens are bone, they are pretty much blind and deaf. The only scent which they have is the scent of smell and it is a powerful one.

The mother cat will start licking and grooming her kittens to imprint her scent on them and the kittens will in turn knead her to leave their scent on her. This mutual exchange of scent signatures is what allows female cats and their litter to recognize each other.

In fact, researchers have also discovered when studying a group of feral cats that the females in heat avoided mating with other closely related cats.

So Why Do Cats Of The Same Litter Still Mate?

two sibling cats sleeping with each other

Even though it has been observed that female cats do filter out mating with a closely related cats male cat, it isn’t always a foolproof plan.

As vigilant as a female cat can be, she might not be able to fend off all male cat siblings that make an attempt to copulate.

Furthermore, animals do lack the ability to be fully conscious and aware of incestuous mating. When the sex hormones take over during mating season, the strong animal instinct to reproduce overrides all rational thinking.

Sometimes, siblings cats mate without even realizing that they are siblings. Cats recognize each other by scent but if you separate the cats long enough, they will regard each other as strangers once the scent is forgotten.

At What Age Do Cats Mate?

Cats reach sexual maturity at a fairly young age of about six months. Some cat breeds even as early as four months of age. Considering that the average life span of a cat ranges between fifteen to twenty years, they do get frisky pretty early.

A cat’s breeding cycle depends on factors like temperature and the number of daylight hours. Indoor cats tend to have long breeding cycles due to having more light.

Cats in heat tend to be very vocal and affectionate. The male cats will start marking their territory with urine and female cats will sound like wailing banshees to attract male cats. Such behavior can drive cat owners up the wall.

What Happens If A Cat Gets Pregnant By Her Brother?

If two sibling cats were to mate, there is still a chance that their offspring will turn out fine and without any birth defects.

It is just that inbreeding cats do bring about a greater risk of having inbred cats with serious genetic defects. And it is a problem that you won’t be aware of until the kittens are born.

Inbreeding For Predictability

Even though inbreeding cats come with a high risk, there are some cat breeders that still do so for the sake of predictability.

Inbreeding refers to the breeding of not only sibling cats but between parent and child.

If you are a certified and well-known cat breeder, there is demand for your cats because of some distinct personality or physical traits that come from your kittens.

It is like a craftsman who has honed his craft to produce the same end result time after time.

And people pay good money for the predictability.

Would you invest $5000 in a stock that is guaranteed to make you 50% gains in a year? Or would you rather ‘invest’ $5000 in a lottery ticket that can make you a million dollars?

I rest my case.

If there are desired traits in the brother and sister cats, the breeder will mate them to pass down these traits in the downline.

Cat breeds like the Persian, Scottish fold or Munchkin are more prone to inbreeding due to their unique physical traits.

Problems With Inbreeding

Although inbreeding cats can help preserve their quality traits, it can also lead to other health and genetic defects in the kittens.

The weaknesses of inbred cats are doubled down as with their strengths. An inbred cat can suffer from congenital abnormalities, autoimmune diseases and growth retardation.

Horrible things for any poor cat to suffer from.

How Can I Tell If My Cat Is Inbred?

Not all inbred cats suffer from the typical issues that come from inbreeding. If you have gotten your cat from respectable breeding that inbreds the downline, your cat should be free of problems.

But if you do not have not much knowledge about your cat’s background, here are some tell-tale signs that it might have been an offspring of inbreeding:

  • Kittens that are small and lethargic
  • Cat looks smaller than the average adult size
  • Queens will experience a larger number of stillborns
  • Cancer at a young age
  • Crooked noses
  • Misaligned jaws
  • Asymmetry facial features

The thing is, there isn’t a 100% sure way to tell if you have an inbred cat. Some cats can exhibit the above symptoms even when coming from parents that are totally unrelated.

How Do You Stop Sibling Cats From Mating?

If your female cat has just given birth to a litter of kittens, there are a few things that you can do to prevent the siblings from mating with each other.

Separate Your Cats

You can make an attempt to separate the female kittens from the males. But do not separate the kittens from the mother cat too early.

The kittens need mother’s milk for nourishment and separating them too soon can cause health and behavioral problems.

Don’t be surprised to see the mother cat being rough with her kittens. This is to teach them respect and how to behave properly.

The best time to separate the kittens is when they start to wean off their mother’s milk. This is when they are about four to six weeks of age.

Sterilize Your Cats

This is probably the best way to prevent sibling cats from mating with each other. Make it a point to neuter or pay your cats once they reach about four months of age.

Kittens can become sexually active once they hit six months old so you don’t really have a big buffer to get them fixed. Once the cats have been sterilized, a little harmless flirting between the cats won’t cause much of a problem.

Do Male Cats Mate With Their Daughters?

It is common for male cats to mate with their daughters. A stud or tomcat that has not been neutered will attempt to mate with a female cat in heat even if it’s his daughter.

This too is considered inbreeding and can produce inbred cats with health problems. If you have no plans to use your male cat for breeding, please get them fixed.

Do Sibling Cats Mate After Being Fixed?

Siblings cats can still go through the process of mating even after getting fixed. This is because they still have sex hormones in their body which will take some time to disappear.

Once these sex hormones have been thoroughly eliminated from the body, the cat will no longer have a sex drive and the desire to mate.


If you are not a certified breeder or have intricate knowledge of breeding cats, please do not attempt to inbreed cats.

There is a high chance of sibling cats breeding with each that can lead to inbred cats with many health problems.

Many of these cats don’t stand a chance of living a healthy life.

As responsible cat owners, we need to prevent such unfortunate incidents from happening.

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