Can You Breed Labrador Siblings?

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When we first got Molly, we were strongly considering bringing home one of her siblings, too. One of the thoughts we had was that we could eventually breed them. However, we started to wonder if choosing to breed Labrador siblings would result in any complications. We did a ton of research as we considered it. I thought it would be beneficial to share it for anyone else that is wondering the same.

So, can you breed brother and sister Labradors? You can, but you shouldn’t. It poses the danger of long-term health complications and has unpredictable consequences. Professional breeders might attempt this to fix certain characteristics or phenotypes. However, for the at home breeder the potential risk is not worth taking on.

On most occasions, it’s a bad idea to breed Labrador siblings. However, it happens more often than you might think. Read on to discover the benefits, risks, and considerations of breeding brother and sister Labradors.

In this article

Dangers of breeding Labrador siblings

The risk involved with breeding sibling Labradors is real; it’s a double-edged sword. You might end up condemning the newborn puppy to a life of suffering. The process of mating closely related dogs (mother/son, brother/sister, father/son) is known as inbreeding.

The major issue with inbreeding is that its harmful effects typically take time to appear in a bloodline. Many inbred dogs suffer at a later age, while some puppies may have congenital diseases. Let’s talk about how breeding closely related Labradors (or any dog breeds) can lead to health complications and physical deformities.

Smaller gene pool 

Each gene gives the animal a particular characteristic, such as resistance to disease, tolerance to the harsh climate, and so on. The combination of all the genes of a population is called the gene pool. It represents the complete genetic diversity found within a species, including even those genes whose effects are not visible in an animal. 

Inbreeding limits the available gene pool and can increase the chances that a dog will pass on harmful, recessive traits to its puppies. And, just to clarify, a recessive trait is one that's only expressed if the puppy inherits it from both its parents.

Dogs, like humans, get one set of genes from their mom and one from their dad. Many negative characteristics of a Labrador (and other dogs as well) will only be expressed when the newborn puppy has two copies of the recessive genes, one from each parent.

For example, if your dad has a harmful, recessive version of a gene and passes it onto you, you won't express it unless your mom gives you a copy of it too. 

Consequently, these genes can hide for generations, secretly being passed down but never expressed. But if your parents are closely related, the chances that they both carry the harmful version of the gene are way higher.

The same is the case with dogs. If you breed brother and sister Labradors, it increases the chances that they may pass undesirable traits.

Inbreeding depression

If inbreeding lowers the fitness of a population, scientists say the population is experiencing inbreeding depression. Let’s discuss how excessive mating of a sibling or other closely related Labradors can lead to inbreeding depression.

First of all, the major reason you would want to breed Labrador siblings is to pass on specific good traits or produce puppies with predictable traits related to appearance and temperament. 

However, there’s no secret formula to ensure that only the good traits get passed on and the bad ones are halted. As a result, a host of undesirable traits are also passed to the next generation, which makes inbreeding counterproductive for both the dog and the breeder.

If a population has larger genetic diversity, it’ll be better prepared to deal with environmental changes or disease outbreaks. This is because a larger gene pool means they’re more likely to have genes that’ll protect them from such hostile changes. 

On the contrary, if a population has a lesser number of genes in its gene pool, it’ll be vulnerable to such problems. It can cause the population to become endangered or even extinct.

Inbreeding in dogs can lead to lower fertility, slower growth, an increase in genetic diseases, and birth defects. Problems like dwarfism and shorter lifespan are common in Labradors because of inbreeding.

Benefits of breeding Labrador siblings

It’s not unusual for any dog to try to mate with its sibling. They lack emotional maturity and so there are no morals or anything. It might even be easier to breed Labrador siblings as they’re already familiar with each other.

As I've said, the most common reason for breeding brother and sister Labradors is to produce puppies with predictable traits. The idea is that if you have two exceptionally healthy, beautiful Labradors, and you breed them together, their puppies will also be strong and healthy.

To breed Labrador siblings would also save you time and effort. You would typically have to spend months looking for a stud that complements your dam. Then, you’d be paying fees and signing a stud service contract. If instead, your dam can be mated with her brother, you’ll save significant time and effort.

Expert breeders may use inbreeding only after carefully examining the possible outcomes and complications. Mediocre breeders only care about getting cheap and pretty dogs, so they can sell them.

If brother and sister Labradors are bred by an experienced breeder, it may turn out well. You’ll have a better idea of what to expect from the future puppies. However, it’s highly recommended that both dogs still undergo genetic screening, so you know the good and the bad things about their genetic material.

Coefficient of Inbreeding - COI

It’s impossible to determine the exact impact that breeding brother and sister Labradors will have on the litter. What we do know is that as the closeness of genes increases in the parent dogs, the risk of having a harmful and severe effect on the breed as a whole also increases.

So how do you measure the closeness of genes or the degree of inbreeding in two Labradors?

We can do it using the coefficient of inbreeding, which measures the common ancestors of the sire and dam. The higher the inbreeding coefficient is, the more likely it is that the potential puppy will inherit two copies of the same gene from its parents. Typically, it’s recommended that the inbreeding coefficient shouldn’t be over 5%.

So, what’s the COI for sibling Labradors? Well, in the case of the parents being brother and sister, the coefficient of inbreeding seems to be around 25%. This puts the potential pup at a highly dangerous level of risk. 

Therefore, you need to make sure that both the sire and dam have a clean genetic profile before attempting to mate them. If any negative genetic material is present, there’s a high chance that the new puppy will inherit it.


So to conclude, if you’re wondering whether or not you should breed sibling Labradors, the answer is no. You also have to make an ethical decision here. How would you feel if the dam gives birth to puppies with congenital diseases or physical deformities? 

The mother Labrador may reject the pup(s) if they’re weak, and they probably won’t survive. It’ll be distressing for you, the mother, and the puppy. You need to consider if the risk involved is worth it.

If you still want to do it, never go ahead without professional advice. Make sure you really know what you’re doing. Remember, there are lives at stake here.