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6 Reasons Adult Siblings Fight

Siblings squabble long after childhood. Here's what they're fighting about — and how to deal with it

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Nadia Hafid

Sibling rivalry may not always reach the level — thankfully — that Cleopatra had with the brother and sister she reportedly had murdered, but they regularly involve jealousy and resentment that often lingers into adulthood.

In fact, 1 in 2 adults still argue and compete with their brothers and sisters, according to a survey by the National Organization for Women. And one-third of respondents say they’ve stopped talking to a sibling altogether at some point in their lives.

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So why all the sibling fussing and fighting? It can’t still be over whose turn it is to empty the dishwasher anymore, can it?

Here are six reasons adult sibling don't get along, and four ways to handle it.

1. Estates/wills

Buried wounds frequently resurface along with emotions that arise from grief and loss, and this increases the possibility of a power struggle, says certified life coach Krystal Conner, based in Atlanta.

When one sibling is the executor of a parent’s will, another may feel less loved, or that they have less control. In addition, the way a parent has left money, property and other resources to children can cause siblings to disagree about how those resources should be doled out.

“If one sibling believes that they contributed more to the care and well-being of a parent, or if a sibling believes they are somehow more entitled to receive in a will, it will create conflict,” Conner says.

According to research from a national financial planning company, when siblings quarrel over finances, it’s usually about their parents (68 percent of the time). The main issues concern how an inheritance is divided.  

2. Birth order

Who was born first, second or third is not something that can affect sibling relationships only in the early years, but also long after everyone’s left the nest.

Firstborn children are often viewed as — and sometimes required to be — the responsible ones their whole lives, expected by parents and other family members to follow the rules, serve as role models, and watch over younger siblings. That adds an extra layer of stress, even well into adulthood, as parents age and need to be taken care of.  

They’re expected to be “the boss,” Conner says.

Second and third-born children have different challenges, Conner says.

“The middle child often feels overlooked and unheard, and the youngest often feels as if they should not be — and often aren’t— held to the same standards,” she says.

And that affects how siblings interact, according to research. A 2023 study in the journal Family Relations found that when parents treated siblings differently, sibling relationships weren’t as strong. Siblings engaged in less affectionate and more hostile interactions, particularly when parents—particularly fathers—failed to provide equal treatment to their offspring.

Mothers have a role to play here, too. One study from Cornell University revealed that 70 percent of mothers in their 60s and 70s felt closer to one child over another.

Whether real or perceived, the effects of favoritism have been shown to last from childhood to later years, even lasting after the death of a parent.

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3. Aging parents

The birth order dynamic routinely plays out once parents need increasing assistance.

“In most families, everyone has a role,” says licensed mental health counselor Jody Mykins, from Irondequoit, New York. “Often, the older child is given more responsibility. This can continue in later life with aging parents; the older child is expected to carry more of the load for caretaking [while] the younger sibling may feel left out of decisions.”

Gender may also come into play. The Caregiving in the U.S. 2020 report, the latest available, showed that the majority of caregivers — 61 percent — who make medical appointments and otherwise provide care to a parent are women. So it’s possible sisters may shoulder a larger burden.

4. Jealousy

If siblings feel there is a limited amount of something — such as love, support, affection or basic resources — they may feel as if they need to compete, especially if their parents weren’t generous with love, affection, praise or support, Conner says.

“Depending on the perception of the child, it can easily appear as if the sibling is receiving something that they were not the benefactor of,” Conner says. “It feels unfair, and fosters a spirit of jealousy.”

5. How families define success

 Mykins says an outgoing child, or one who reaches high levels of achievement in academics or athletics, “may receive more parental attention than a sibling who is quiet and introverted.”

That can cause sibling rivalry. Siblings can become resentful when parents focus heavily on the child that, say, earned a college diploma, while ignoring or downplaying the success of another child who didn’t seek higher education.

If that is not how a family defines success, then the parents may not think, “He has a good job, he supports his family, he’s happy,” Mykins says.

6. Grandchildren

A sibling with children may spend more time with their parents than a sibling without children, leaving the latter feeling ignored, Mykins says.

If this is the case, she continues, have a conversation. It's perfectly reasonable to bring up that the family doesn't consider that the childless sibling might want to host for the holidays, for instance.

Or the aggrieved sibling could say, “We always plan things around their schedule. I don’t feel as important.”

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Strategies for coping with sibling rivalry

Be proactive. Mykins, 56, suggests having open discussions with siblings about unhealthy relationship patterns before a crisis arises.

“Don’t wait until your dad is in the hospital, or your mom needs nursing care, and you need to figure out quickly what to do,” Mykins says. Waiting only increases stress, which can increase tensions.

And if you're dealing with an estate or will, get a neutral third party ahead of time. They can minimize the strain by making sure the intended desires of the will are realized. Siblings entitled to the same assets but unable to agree may decide to liquidate them and split the proceeds.

The conversations may not be easy, but there are ways to mitigate damage.

“Be honest, open, willing to listen to the other person and willing to consider making a change,” Mykins says.

Look inward. The only thing that we can control in this world is ourselves, Conner says.

“The root cause of conflict is the perception of each of the participants in the conflict,” she says. “It is their thoughts about what is, what should be or what shouldn't be.”

Conner advises doing some self-reflection.

“The first step is always going to be an acknowledgment that you have some ownership to the rivalry—no matter how big or small,” she says. “Making a decision to address your part, and to do your work is critical.”

 Specific questions to help with self-reflection include: Why do I feel this way about my sibling? How have I contributed to this conflict between me and my sibling? What type of sibling do I want to be for them, regardless of what they do?

Answer honestly and decide whether there are alternatives for why you may feel the way you do, Conner says.

Set boundaries. Setting healthy boundaries with a sibling isn’t about handing down an ultimatum. Think of it as an act of love to buoy your bond.

“Boundaries let your sibling know exactly what is and is not OK with you in terms of your relationship,” Conner says. “Oftentimes, people get upset when their ‘imaginary boundaries’ are disregarded and violated, when the reality is they have never been clearly communicated—or they have been communicated, but the consequence for the boundary is never actually followed through with.”

This isn’t easy. Especially if a boundary is outside of what is expected within the family dynamic, holding tight to it “can be scary and possibly alienating,” Conner says.

Be open. A sibling rivalry is two-sided, Conner says, so you can make the decision to participate in that rivalry, or step away.

“Developing a deep self-awareness will allow you to show up in the relationship in a way that makes you feel proud of who you are being,” she adds. “When you aren't clear on who you are being and how you are showing up, you don't grow or make adjustments in order to be the best version of yourself.”

Because family issues frequently get messy, it can be good to have a therapist listen to conversations and weigh in.

Says Mykins: “It may be an opportunity to heal some very old wounds.”

Editor's note: This article was originally published on January 6, 2023. It has been updated to reflect new information.

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