Aside from borrowing each other’s clothes and having a shoulder to cry on, it turns out there are real tangible benefits to growing up with a sister: a new study found that they are happier, kinder and more optimistic.

The findings by De Montfort University and Ulster University found that sisters encourage each other to talk about their feelings more, which in turn provokes a better mood. The survey spoke to 571 young people between 17 and 25 about their general happiness levels, assessing issues from positive outlook to their general mental health, with sisters coming up tops.

“Sisters appear to encourage more open communication and cohesion in families,” explained Professor Tony Cassidy. “However, brothers seem to have the alternative effect. Emotional expression is fundamental to good psychological health and having sisters promotes this in families. It could be that boys have a natural tendency not to talk about things. With boys together it is about a conspiracy of silence not to talk. Girls tend to break that down.”

He went on to explain how the research could be used by health professionals to help families going through trauma, such as a divorce, “I think these findings could be used by people offering support to families and children during distressing times. We may have to think carefully about the way we deal with families with lots of boys.”

This post was written by Rebecca Cope. It originally appeared on our sister site, Grazia.

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