Though many psychologists have explored the child-parent relationship, most children have a sibling, and these relationships strongly influence their lives. According to Aarhus University researchers, children are highly motivated to make the emotional investment necessary for sibling relationships to work. This is true even in complex situations, such as following a divorce or in large families, says the team led by Dr. Ida Wentzel Winther, an associate professor at the Danish School of Education.

Nine out of 10 children have siblings, say Winther and her colleagues. What do siblings mean to each other, especially in circumstances of change, such as divorce? (Ex)Changeable Siblingships, their anthropological research project, turns the spotlight on 94 grade school- and high school-aged participants. During extensive interviews, the children discuss and explore their interactions with brothers and sisters, which the researchers take care to differentiate.

“We regard sibling groups as “long” when there is a relatively large age gap between the youngest and eldest sibling,” wrote the authors in their project eBook. “Wide” is the term they used for children who are part of several different households with different parents. “Short” characterizes children who are fairly close in age, while “narrow” is applied to those who share parents and live under the same roof.

The researchers say children of divorced parents, whether their sibling relationships continue as wide or narrow, are highly adaptive. A number of the children spend time between more than one home and among different groups of siblings. Turns out, these circumstances help kids become better at commuting, logistics, and relating to others.

Yet, despite having developed strong "adaptability muscles," children of divorced families are still deeply affected by their siblings' movements. In particular, one boy in the study expressed his emotional confusion by telling the researchers his parents had divorced. However, the team soon learned his parents had not divorced. Instead, his parents explained, his two older sisters live with another family every third week and so the boy keenly feels this disruption each time they leave and return. He wishes he knew more about his sisters’ lives, he confided to the research team.

Whether in grade school or high school, the participants said their siblings were at times affectionate. Asked if they would hug a friend the same as their brother or sister, all said “no.” Long, short, wide, or narrow family relationships were alike, with most of the children reporting a warm relationship with their brothers and sisters. Yet affection was not their only bond. On occasion, a sibling might throw a random punch or slap. Once again, participants say they would not get physical in the same way with their friends.

With cell phones, social media, and Skype, the researchers find young siblings can interact and connect without face-to-face contact and this provides greater flexibility for maintaining their siblingship. “Interactions are no longer connected to a physical place, to timekeeping or the calendar,” the researchers wrote.

No matter whether children live with one family at a single address or with multiple families in multiple homes, their relationships with brothers and sisters depend on unique dynamics, the researchers conclude. Capable of working out their own relationships without parental interference, kids strike a delicate balance between closeness and distance, similarities and differences, and continuity and change. Why not see for yourself? The video below captures 30 of the participants during their interviews: