There is nothing more likely to get the day off on a bad foot than listening to your children release their inner warrior on each other. Generally, these bickering squabbles occur over some of the most mundane things I can imagine.

‘‘But SHE got more M&Ms than me!’’

Really kid? Who has the time to count out exact measurements to make sure you didn’t get jipped one extra sweetie? Yet there I am counting out the exact number of M&Ms in equal measure, pre-emptively ensuring the correct amount is placed in the proper colored bowl. Because we all know that would be the next argument right?

Favorite items, who sat in the front seat last time, who touched someone else’s shoe…Heck, my eldest daughter has even resorted to complaints over the noise my middle son makes when he is chewing. It is exhausting and sometimes the list feels so long, and unimportant in the grand scheme of things, that I get extremely frustrated at my kids fighting. I wondered what was causing this, how common it was, and more importantly how I could stop my kids from releasing their inner Viking on each other, so I decided to do some research.

What exactly is sibling rivalry?

Most of us are familiar with sibling rivalry, experienced personally in life, or seen depicted in numerous movies or TV shows. Usually humorous siblings fighting in prank wars, or more darkly with sibling jealousy ruining each other’s relationships.

The official definition of sibling rivalry is verbal or physical fighting between siblings, which includes name-calling, hitting, tattling, and bickering., but also includes things like immature behavior (mocking or sticking tongue out) or voicing feelings of envy, unfair treatment, or wanting to get rid of the other sibling.

Most of the more intense competitive behavior exhibited between siblings fighting is usually to gain the attention of their parents, with aggressive behavior rooted in a feeling of jealousy or being “left out.” Some children may even revert to more immature behavior to gain back a dependent role and be more reliant on their parent again. An example of this is when a new baby joins the family and the toddler starts wetting the bed, crying, or talking like a baby again. The parents’ attention has been diverted to the care of a baby and suddenly the toddler feels a bit usurped in his “look at me” role.

How common is sibling rivalry?

Most likely if you grew up with a sibling, you probably experienced some level of sibling rivalry. If you didn’t and you were lucky to grow up with a sibling who was your best friend, I envy you. I remember growing up in a virtual war zone with my sister. I would look at other families and see sisters who went shopping, shared clothes, and were best friends. Yet my little sister hated anything that came from me. She could come up with an idea, and if I agreed with her, suddenly it was terrible. As kids, we had different views, opinions, and even a different perspective on life.

Sadly this great divide has existed well into adulthood, yet we are not alone as 1 in 3 adults describe their relationship with their adult siblings as rivalrous or distant. This is likely due to the fact that even as adults we get cast in familiar roles, and if one of the siblings cannot see a new perspective, the relationship can’t be mended. As a mother, this is something I am keen to avoid happening between my children.

While I know that some level of child fighting is ultimately a natural part of growing up, I was convinced there must be something I can do to help. As parents, that’s what we tend to do right? Try and do better than our parents before us, if only just so we don’t pull our own hair out from the squabbling.

Levels of sibling rivalry are fluid and it will change over time between siblings, and particularly at different life stages. Younger children tend to express sibling rivalry in more physical ways such as grabbing, pulling, or breaking a favorite item, or trying to get a sneaky smack at the new baby. Older children tend to be more verbal calling their siblings names, yelling, or slamming doors. Typically sibling rivalry tends to peak around ages 10 to 15, which isn’t surprising since they all seem to lose their minds around that time in general. Brothers who are best friends in primary school may end up virtually cage fighting by high school, then be inseparable as adults.

It is reassuring to know it is normal with or without my parental influence. Parents can contribute to or worsen existing rivalry, but we can’t stop it completely as it is a natural part of the family dynamic.

What is the cause of sibling rivalry?

Why do siblings fight in the first place, particularly over things that seem irrelevant to adults? Many people have surmised that it is due to a competition for resources. This can be for material items like toys or food, but also for more abstract resources such as parental love, affection, or praise. When one sibling observes or feels that they are receiving less than before or less than a sibling, it leads to dominant behavior.

So is it about money? Well no, not at all. Sibling rivalry occurs in all different types of families in every social class. From wealthy siblings squabbling over inheritances to low-income families fighting over the best toy. Yet the very things that divide can also cause siblings to bond together. Siblings consoling each other over the loss of a family member, or 2 children sharing their last piece of bread. While lack of money can increase the stresses and lower the amount of resources available to the family as a whole, it clearly doesn’t cause sibling rivalry. Equally no amount of money can necessarily fix a deep-rooted sibling divide.

It also has nothing to do with the size of the family. While the number of children increases the odds for the family to experience sibling rivalry, it isn’t necessarily the cause of all the fighting. It occurs in smaller families with only 2 children constantly picking at each other and in larger families with 4 or more children. The best way to demonstrate this is through an example of flipping a coin. If you flip a coin twice it is relatively likely you may get 2 heads (and both children will get along). If you flip the same coin 6 times, it is unlikely they will all be heads. So the number of children in the home doesn’t necessarily cause sibling rivalry, but it certainly increases the odds that one or more of the children will start to feel left out.

Certainly, the division of parental attention and assets means each child “gets less” than in a smaller family, but some larger families actually have a greater bond and sense of teamwork. Older children are usually tasked with helping take care of younger siblings, creating a deeper, more meaningful bond with their younger siblings. Therefore it isn’t necessarily about the number of children, but more about the dynamics and perspective between them all.

While there are some factors that have little influence on the level of sibling rivalry, for instance, their ages or genders, it happens in all families to some degree. And while we can’t completely stop it, and certainly didn’t start it, there are things we do as a parent that can add fuel to the fire so to speak.

What can make sibling rivalry worse?

Normal life stressors tend to inflame sibling rivalry the same as it does between a husband and wife or roommates. Suddenly the way they put the milk in the fridge or leave a teabag in the sink just tips you over the edge into a mad fury. It really isn’t about the milk or the teabag, is it? It is about 100 other little nit-picky things and it was just the straw that broke the camel’s back.

Siblings are pretty much in the same boat. They are with their siblings all the time, many go to school together, childcare together, have to share time with family members. Even when you as a parent get a break while they are at grandma’s house…guess who is still tagging along?

Combining the normal level of rubbing each other’s nerves raw, with an increase in life stressors, the temper tantrums, and name-calling may boil over. Individual differences in temperaments or personalities, as well as changes in the daily routine, can increase the stress on children. Perhaps a new addition to the family via a baby sibling or maybe the presence of a new partner or stepsiblings has caused an unexpected divide. The new addition forces a whole new dynamic within the family where roles are no longer clearly defined and the balance starts to shift around.

Similarly, if a child has special needs or becomes ill, a parent will naturally be more focused on them. Other siblings view the ill child as receiving more attention, and young children can’t consciously discern the difference between loving fun attention and dutiful caring attention. For them, it is just viewed as a differential treatment that they don’t understand.

Another thing that can increase sibling rivalry is the natural progression of children through different life stages and their evolving needs as individuals. It is inevitable as older children grow they need to gain independence and trust and therefore get different treatment from younger siblings. Perhaps the oldest is now a pre-teen and needs a cell phone to check in while out with friends. As a parent, you are trying to build responsibility and trust with your oldest, but the 9-year-old wonders why they don’t get a phone “to play with.” Or maybe that same 9 year old is complaining he has to wash the dishes while his 5-year-old brother (who can’t even reach the sink) isn’t helping. The treatment is viewed as “unfair” by certain siblings, but it usually stems from the difference in ages and stages of development.

Finally, parents can inadvertently worsen sibling rivalry through their own actions. Children as young as 1 year old are able to determine and ascertain differing levels of parental treatment between themselves and siblings. Constantly praising or criticizing one child over another, encouraging competition between siblings, labeling your kids as the “kind one” or “smart one,” or clearly showing favoritism for one child’s wants and needs, all exacerbate sibling tension. An increase in parental affection toward one child can directly cause more hostility and conflict with siblings.

Favoritism or preferential treatment of one child is directly linked to an increase in both sibling rivalry and a reduced parental relationship for the “unfavored” child. The child who receives preferential treatment can become overly confident in themselves, and view their worth as greater than others, particularly the disfavored child. The child who is perceived as less favored then always feels the need to compete and “be as good as” the favored sibling, resulting in lower confidence and self-worth. If this proceeds into adolescence, then the favored child is more likely to have good mental health and do better academically, while the disfavored child may start to exhibit risky behavior or even substance use problems. In fact, even when parents feel they treat children equally, the very perception of a parent’s differential treatment is enough to create tension and distance within the parent-child relationship.

What are the consequences of extreme sibling rivalry?

While some amount of mild sibling rivalry is normal, it is important to understand that physical and verbal abuse is never okay. This applies to the parent-child relationship, but also in the relationship between siblings. Nearly 30% of children experience a very severe form of sibling rivalry termed “sibling bullying.” This happens on average when a child is around 8 years of age, and for the most part is described as “psychological” bullying, which includes name-calling or “being made fun of.” Being the firstborn or an older brother is more likely to put you in the role of a “bully” to a younger sibling.

Additionally witnessing domestic violence, turbulent parental relationships, or experiencing aggressive or neglectful parenting, also increases the chance a child will bully other siblings or peers. Being the victim of bullying by an older sibling, peers at school, or by a parent is also a contributing factor leading the victim to go on to bully a younger sibling or school peer. While a mild amount of sibling rivalry is normal, sibling bullying can have lasting adverse mental health effects that can persist into early adulthood, most of which result in increased loneliness, difficulty making friends, delinquency, and mental health problems such as recurring depression, self-harm, or eating disorders.

Don’t despair if your kids are at each other’s throats, as we have some tips on how to deal with sibling rivalry.