People's lives are full of relationships with varying degrees of permanence. Friendships come and go, spouses, which typically arrive in adulthood, aren't always forever, and parents eventually die. But it's the relationship between siblings that usually proves the most enduring – there at the start and long after the parents are gone. It is also among life's most important.
Research shows the sibling relationship is crucial to emotional well-being. The Harvard Study of Adult Development shows a close relationship with a sibling during the college years is the most reliable indicator of emotional health at age 65 – more influential than childhood closeness to parents, parental divorce, marriages and career.
But what makes a sibling relationship healthy? How does one define being "close"? And what happens if you're not?
"A healthy sibling relationship, like any strong friendship, is characterized by love, respect, concern, consistency and reciprocity," said Fern Schumer Chapman, author of "Brothers, Sisters, Strangers: Sibling Estrangement and the Road to Reconciliation." "Siblings should expect to have conflicts, but in a healthy relationship, they feel confident that there will be repair and forgiveness."
Research on sibling support and closeness is associated with less loneliness, lower levels of depression and greater life satisfaction, Chapman said. Yet her research shows a third of people describe their sibling relationship as hurtful or strained, even if many don't talk about it.
What close sibling relationships offer
Close sibling relationships provide a shared family history that's revisited and validated.
"A lot of times it's a situation where one person is saying: 'I went through that too. I remember that particular phase in our family,'" said Ali-John Chaudhary, a psychotherapist who runs the website Sibling Estrangement. "It can also give you different perspectives and variety to a shared experience."
Healthy sibling relationships are facilitated by parents who create a culture of respect and open communication. If a parent sees a power struggle, they intervene and try to foster a sense of cooperation and inclusivity. Parents foster healthy sibling relationships by giving their children skills in conflict resolution. No sibling is favored, and children are not compared in behavior, intellect or appearance.
When children become adults, they must carve out time to nurture sibling relationships themselves. The need to approach their sibling with a sense of curiosity, especially when there are personality differences.
"It really is about ... a sense of respect for one another, making room for one another, which would foster that sense of emotional intimacy," Chaudhary said. "Once you get to know your sibling, you find out what their interests are, you find out what it is that makes them tick, you start to identify what matters to them, so it becomes a give-give relationship."
When siblings fight
Several factors can lead to the deterioration of a sibling relationship.
A large age gap between children can prevent siblings from having shared experiences, an important part of bonding. Family trauma, differences in political views, addiction and mental health struggles also can challenge sibling relationships. Ruptures also can occur when a sibling breaks from the family identity, such as marrying someone the family doesn't approve of.
Chapman points to Prince Harry, who acknowledges that his relationship with his brother, Prince William, has grown distant.
"The brothers both experienced the death of their mother, which is a deeply traumatizing event. A second risk factor is parental favoritism, and the monarchy presents the ultimate in favoritism, since William's going to become king and Harry will always be relegated to a supporting role. The monarchy is also notoriously bad at resolving personal problems. ... And Harry married far outside the family identity."
Siblings often go through periods of distance
Since sibling relationships are among life's most enduring, experts say, they will wax and wane over the decades.
"There will come times when you're much closer, and when you are much less intimate," Chapman said.
In her memoir, Chapman wrote of her brother, noting that "like all brothers and sisters, Scott and I are at times pulled toward each other, and other times we both need
distance. A sibling relationship is a kind of living organism that is always changing."
Chapman said there are periods when a sibling relationship is especially vulnerable, particularly when family members redefine their roles. This can happen during adolescence, when new boundaries are set. Anytime a sibling creates a new identity – when they leave for college, or a new job, there is a risk of a rift. When her brother went off to college, Chapman said, there was a deep sense of abandonment that haunted her.
Marriage is also a risk factor for sibling tension. A new brother or sister-in-law may want to limit or control the couple's involvement with one side of the family.
The birth of a baby can also be difficult. A sibling begins to focus on his new or her new family, and the other sibling can feel abandoned or betrayed. There are also instances when siblings start to compete with one another through their children, particularly for grandparents' affection.
Parental illness or death, especially when inheritance is involved, is also a ripe time for conflict, with siblings competing for money, power or love.
Sibling estrangement is painful, and reconciliation takes work
When two siblings become estranged, especially when one still wants a relationship, Chaudhary said, it can lead to mourning.
For 40 years Chapman had almost no relationship with her brother. She'd see him across the room at a funeral and feel she was looking at a stranger. It got so bad, she wasn't sure she'd recognize him on the street.
"This is a uniquely painful experience," she said. "It's not like a death, where there's no negotiating. In this case, you have a situation where somebody who you thought would be a sustaining relationship throughout your life has made the choice, even though they're still walking the earth, to have nothing to do with you. It's a fundamental shunning."
Some sibling relationships are too toxic to repair, and others will need to remain limited. Dealing with a difficult sibling may mean establishing firm boundaries. For estranged siblings, reconciliation is possible only if all family members feel safe and there isn't a risk of further abuse or retraumatization.
Chapman said early conversations during reconciliation are best facilitated by a therapist. Siblings will have to listen without interrupting or challenging each other's stories, to acknowledge, with empathy, the other person's hurt or alienation, and to let go of anger.
Sibling relationships are among the most important for emotional well-being, yet they are also among the most complex. These relationships feature a constant push and pull between warmth and animosity, rivalry and friendship. Rifts between them can be the most painful, and intimacy within them can be the most rewarding.
"This person is familiar with your family history, with memories you may have experienced, with the things you may have forgotten. It's somebody who knows what you've been through. It's what you're left with once the parents are gone," Chaudhary said. "It is a relationship we are ideally able to experience, and if we can't, then it's important to make decisions based on what we feel is nourishing and empowering for us."
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This article originally appeared on USA TODAY: Sibling rivalry, fighting or estrangement is bad for your well-being