“I am the middle child in a sister-trifecta, so I know all about how sisters can wear on your nerves one minute and feel like your best friend the second. At the end of the day, we were a loving — albeit totally dysfunctional — family, and I’ve learned a lot about the world and myself just by having them in my lives.

That’s not surprising, though: Research shows there are many proven benefits to sisters. (As hard as it may be to believe when she’s “borrowing” your favorite sweater for the 10th time.)

“They help you develop social skills, like communication, compromise and negotiation,” says Alex Jensen, assistant professor in the School of Family Life at Brigham Young University and the author of research into sibling relationships. ‘Even sibling conflict, if it is minor, can promote healthy development.’”