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Questions And Answers

Can Hamsters Breed with Their Siblings?

Last Updated on: 25th September 2023, 11:43 am

Hamsters have a high drive to breed once they reach sexual maturity. They don’t recognize siblings from the same litter as their family, so brothers and sisters may mate.

Sibling hamsters should never be interbred. While parent hamsters can mate with children, hamster pups born to brother and sister pairings have severe genetic defects, which assumes the pups aren’t stillborn and survive more than a few days.

Sometimes, a hamster born to sibling parents will have a prominent health issue, such as a misaligned spine or teeth. The repercussions of sibling interbreeding can sometimes be more subtle and only manifest later in a hamster’s life.

Issues connected to sibling breeding in hamsters include an enlarged prostate in males, epilepsy, heart defects, rapid loss of fur, paralysis in the hind legs, and sight problems.

Hamsters will attempt to breed with their brothers and sisters once they reach sexual maturity. So, hamsters should never be kept with members of the opposite sex once they’re 6 weeks old.

Will Hamster Siblings Attempt to Breed?

Animal Behavior confirms that hamsters can recognize conspecifics by unique odor. Unfortunately, hamsters don’t understand why they recognize each other.

Sibling hamsters housed together will likely attempt to breed upon reaching sexual maturity. A male will acknowledge and recall a female’s unique scent but won’t comprehend the familial relationship.

Can Hamsters Mate with Siblings?

Two hamsters of the opposite sex and the same species can and will breed. Mating and insemination will unfold the same way as with two unrelated hamsters.

The bigger question is, “Can sibling hamsters have babies?” According to Laboratory Animals, interbreeding between small mammals like hamsters has a high mortality rate.

Hamsters have a high drive to reproduce and propagate their species. To this end, it’s advisable to separate male and female siblings by the time they reach sexual maturity at 6 weeks of age.

This will apply exclusively to siblings. Many hamster species can mate mothers with sons and fathers with daughters without ill effect. However, brothers and sisters from the same litter won’t be successful.

can sibling hamsters have babies?

What Happens if Sibling Hamsters Mate?

Having established that hamster siblings won’t necessarily recognize each other as family, we need to address another question: what happens if you breed brother and sister hamsters?

The risk of genetic defects is high in the unlikely event the offspring survive. Often, hamsters bred between siblings are born with deformations like spinal misalignment and dental malocclusion.

Even if the hamster pups appear healthy to the naked eye and aren’t rejected or killed by their mother, many issues often present themselves later in life.

The Bulletin SPEP used interbred hamsters as a model for animal inbreeding and identified 6 common effects that manifest throughout what is likely to be a short life for the hamster:

Hair Loss

One of the most common symptoms of interbreeding found in hamsters is loss of fur. Pups born of sibling parentage may initially grow fur as normal, but issues will soon present themselves.

In some cases, the fur will grow erratically and not cover the hamster’s entire body as it should. In others, the fur will grow as expected and fall out in tufts.

If a hamster lacks fur, it’ll struggle to maintain an appropriate body temperature.

A hamster’s soft, delicate skin is also easily damaged without a protective layer of fur, increasing the risk of cuts and wounds that invite bacterial infection.

Hind Leg Paralysis

Hind leg paralysis is another common concern in interbred hamsters. This issue is frequently linked to damage to the spinal cord.

As discussed, hamsters born to brothers and sisters frequently have a misaligned spine. The issue may be present below the skin, unseen by the human eye until too late.

While a hamster may be able to live its life without the use of hind legs, it’ll be increasingly problematic. The hamster will find exercise difficult and unable to indulge in recreation like climbing.

Hamsters with paralyzed hind legs will also find it difficult to groom themselves. As well as being distressing for such clean animals, this increases the risk of conditions like flystrike.

Muscular Dystrophy

Even if a sibling-bred hamster isn’t automatically plagued by hind leg paralysis, the likelihood of developing muscular dystrophy is significantly increased.

The hamster will have weak muscles that struggle to perform basic tasks, cutting its life short.


Cardiomyopathy is a hardening of the tissue around the heart, making it hard for blood to pump around the body. This is a common concern in sibling-bred hamsters, leading to heart disease.

Hamsters with cardiomyopathy will grow breathless when exercising and can be prone to cardiac arrest. A hamster’s heart is small and vulnerable, with a disease exerting further strain.


Epilepsy and a higher likelihood of seizures can be hereditary in hamsters.

Typically, any hamster with a history of seizures will be removed from a breeding program, as this condition can arise uniquely in a hamster born of otherwise healthy siblings.

Seizures in hamsters follow the same pattern as those in humans and other animals. The hamster will drool, convulse, and potentially lose control of its bladder and bowels.

It’s also common for a hamster to lose consciousness during a seizure.

It’s common for hamsters to break bones in the spine or neck while convulsing. The pressure and shock placed on the heart of a sibling-bred hamster can lead to an early death.

what happens if you breed brother and sister hamsters?

Retinal Degeneration

Some interbred hamsters have anophthalmia, making it look like they’re missing one or both eyes. As per Investigative Ophthalmology, some tissue will remain, but the hamster will likely be blind within two weeks.

Most hamsters grow considerably more dependent on their senses of hearing and scent to negotiate the world, so if a sibling-bred hamster is blind for life, it won’t be too concerned.

How to Avoid Sibling Hamsters Mating

Hamsters must live independently after 6 weeks, so they become territorial and aggressive at this age.

With dwarf hamsters that live in colonies, it’s harder to keep siblings from breeding. The only way to be effective here is to sex the hamsters early and separate them based on gender.

There are two core ways to determine the gender of a hamster:

  • Males don’t have nipples, while females have 6 pairs of nipples along each side of the belly.
  • A male hamster’s penis and scrotum should be visible from 4 weeks of age, although the testicles sometimes retract.

If you keep hamsters apart, they’ll have no opportunity to breed with siblings. Be vigilant about this, as female hamsters enter heat every 4 days, so there will be many opportunities to mate.