Sure, they can be a pain sometimes, but beneath all the arguments, eye rolls, and slammed doors, there's just something about having a sister that makes life, well, better. And there's research to prove it.
The results of a 2010 Brigham Young University study published in the Journal of Family Psychology show that having a sister can boost mental health and self-esteem. Regardless of whether she is older or younger, researchers found that a sister helps protect her siblings from "feeling lonely, unloved, guilty, self-conscious and fearful."
The study involved 395 families with more than one child, including at least one between the ages of 10 and 14. The adolescent child was videotaped while answering questions about a sibling closest in age. Researchers then followed up with the families a year later.
"What we know suggests that sisters play a role in promoting positive mental health," Alex Jensen, assistant professor in the School of Family Life at BYU, told Motherly, "and later in life they often do more to keep families in contact with one another after the parents pass."
But that's not to say that brothers don't matter. Researchers found that affectionate siblings impact each other in positive ways no matter their age, gender, or how many years there are between them.
"Sibling affection from either gender was related to less delinquency and more pro-social behaviors like greater kindness and generosity, volunteering, and helping others," the study's lead author, BYU professor Laura Padilla-Walker, told ABC News. "Even if there is a little bit of fighting, as long as they have affection, the positive will win out. If siblings get in a fight, they have to regulate emotions. That's an important skill to learn for later in life."