This Is How Growing Up with Siblings Affects a Cat

In the first few weeks of life, littermates form an extremely close bond; they become important teachers and companions to each other, which significantly impacts their adult lives.

The relationship between feline siblings can often seem mysterious to humans. To unravel this mystery, we will explore in detail the role of siblings in a cat’s life and how this bond influences their behavior.

Siblings Are Almost as Important as the Mother in a Cat’s Development

For a kitten’s healthy mental, physical, and emotional growth, the bond with its mother is crucial—but the role of littermates is just as significant. While it was once believed that kittens could be separated from their mother and littermates as early as 5–7 weeks of age, it is now generally recommended that they stay together for at least 12 weeks.

The first seven weeks are a critical socialization period during which kittens begin to interact and groom each other. The period between the 7th and 14th weeks is the most active play phase. Physical coordination and social skills develop here, including the establishment of hierarchical rankings.

Kittens observe their mother and siblings while they start playing with objects and animals in their environment. These interactions include chasing, pouncing, ambushing, jumping, cuddling, wrestling, and grooming each other. Actions like grabbing, throwing, pawing, and holding objects are also learned from littermates. This period is fundamental to their development, as they learn the essential rules of being a cat.

A kitten’s brain development is closely linked to regular daily interactions during the first seven weeks. Kittens that are frequently handled and played with tend to be more curious, playful, and more likely to develop a larger brain volume. More active kittens in the litter can help their shyer siblings feel safer while exploring the world together.

If kittens are separated too early from their mother and littermates, they often fail to develop proper social skills. For example, during play, they learn how hard they can bite without causing pain. Kittens separated too soon are more likely to become anxious, aggressive, or develop other behavioral issues, as well as have reduced learning abilities later in life.

The Benefits of Adopting Multiple Littermates

When a kitten arrives in a new home, the unfamiliar environment can be frightening, especially if it is alone. This is why adopting two or more siblings together can be extremely beneficial, as their existing bond helps them feel safer.

Even in this scenario, if possible, it’s best to bring kittens home before a long weekend or during a few days off work. This allows you to spend more time with them, helping them adjust to their new home and build a relationship with you.

However, before adopting multiple kittens, you should carefully consider all factors. For example financial situation, available free time, space, the number and temperament of existing pets, and future plans (such as moving or having children).

The Littermate Syndrome

There can be potential downsides to siblings growing up together. Littermate syndrome is a social phenomenon that, in some cases, affects siblings from the same litter. Two siblings can form an extremely close bond that may exclude other animals or even humans from their social circle. However, this condition is widely debated and is generally considered more common in dogs, as they are naturally pack animals, unlike cats.

While some cats are more social and enjoy spending time with other cats or humans, others prefer to be the sole ruler of the household, content with their owner’s presence and security. Each cat is unique, with its own needs and preferences, so it is essential to consider these factors when shaping their personalities.

How Littermates Behave as Adults

Kittens separated early in life tend to forget each other, as they primarily recognize one another by scent. Two littermates separated for a long time will develop entirely different scents, and if they reunite, they may behave as if they have never met before. However, if they live together again, their bond can deepen just as before. Still, they might only tolerate each other or, in some cases, may not get along at all.

Kittens raised together can maintain their friendship into adulthood. However, changes such as sexual maturity (competition for attention, territorial disputes, etc.) can cause them to drift apart, and their relationship may never fully recover. In most cases, though, littermates establish a close bond in their early weeks that they retain later in life. However, predicting how this dynamic will evolve is impossible—just like human relationships, feline bonds change and develop over time.

How to Help Littermates Maintain a Good Relationship

Every cat deserves a peaceful and secure home. If your cats feel happy and safe, they are less likely to feel threatened by territorial intrusions or conflicts. It’s important to enrich their environment with cat trees and toys and to spend one-on-one time with each of them to ensure no one feels neglected. Also, make sure each cat has its own food and water bowls, sleeping space, and litter box.

Despite Being Siblings, Their Genetics Can Be Quite Different

Although it may seem surprising, feline siblings often have significant genetic differences. If mating occurred in an uncontrolled environment, kittens from the same litter could have different fathers. This phenomenon is called superfecundation. Even when siblings share the same parents, they inherit random genetic combinations, making each littermate genetically unique—except for identical twins.

Identical twins in cats develop from a single fertilized egg that splits early in development, forming two separate organisms with identical genetic information. However, unlike in humans, identifying identical twins in cats can be challenging. The genes responsible for coat patterns may express differently, even if their genetic information is the same. (A DNA test is the only way to confirm identical twin status.)