5 Reasons Adult Siblings Fight

4. Personality differences​

Biological siblings share genes, but not usually personalities, and that can cause rifts.​

Mykins says extroverts are more likely to have strong opinions, be social and be externally motivated, which can come across as domineering. Introverts are more likely to be internally focused, putting a lot of thought into opinions that may not be expressed, which can come across as disinterest or lacking emotion. An ambivert has features of each.​

It’s like when “one sister is the cheerleader and the other is the bookworm, or one brother is the football star and the other is the science geek,” Mykins says. “This doesn't necessarily change with age.”​

Siblings can still get along and respect each other’s differences, but sometimes it causes conflict. ​

5. Estates/wills​

Buried wounds frequently resurface along with emotions that arise from grief and loss, and this increases the possibility of a power struggle, notes Conner. When one sibling is the executor of a parent’s will, for example, 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. 

According to research from Ameriprise Financial, 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.

A neutral third party 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.

​​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,” says Mykins. Waiting only increases stress, which can increase tensions.​

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,” says Mykins.​

Look inward​

Siblings often get caught up in playing the blame game, Conner says. ​

“We very rarely challenge the things we believe to be true about ourselves,” she says. “Whatever we spend decades thinking, we just accept as fact. To break out of that, you have to ask yourself, ‘Is that true?’ or ‘Is that true all of the time?’ ”​

Even better, ask yourself if that’s who you want to be. “It's important to know how you want to show up in your relationships,” she says. ​

Conner advises taking control of how you act, regardless of what anyone else says or does. If you have a reaction, understand that the reaction comes from your own thoughts and not someone else's words or behavior.​

She has personal experience with this as a middle child.​

“I could be mad at my older sister, and think, ‘I’m angry because she said these words to me,’ but the truth is, I'm angry because of the thoughts I have about the words she used,” Conner explains. “The reason it's important to attach feelings back to thoughts because that's literally the only thing we can control.”​

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.​

“Oftentimes we don't set boundaries because we fear they will make us look bad or rock the boat, but we end up getting very upset because the person violates an imaginary boundary they don’t know exists,” says Conner. Instead, boundaries “are a sign of love and create a healthier relationship.”​

If you don't want your sibling talking negatively about the family, an example of a boundary would be to get off the phone or walk away — after you’ve made clear what you will and won’t accept, of course.​

Then follow through. Says Conner: “A lot of times we don’t do it, but that’s the important part.”​

Be open​

“A sibling rivalry is optional,” says Conner. “You might be in a healthy relationship, or in one that doesn't need to be very close. You get to make that decision.”​

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.”​