Mary-Kate and Ashley Olsen have likened their sisterly bond to a ''marriage''.

The twin sisters think their friendship and bond is more like a ''partnership'' than just a sibling relationship and they have been developing their bond over the last 32 years.

Ashley said: ''We do everything together ... It's like a marriage and a partnership. We have had ups and downs. It's been 32 years of learning how to communicate.''

Whilst Mary-Kate added to WSJ magazine: ''We came out of the womb doing that.''

The pair are even able to tell when one of them is sad or needing help.

Ashley said: ''We're together every day, probably from 9 a.m. till 12 at night, sometimes earlier ... We definitely feel it [if they need each other]. And also, you know, we're mirror twins, so we also kind of go like this [and balance out]. One's really good, the other's not so good, it's kind of this balancing act.''

The twins have also been a lifeline for their younger sister and actress Elizabeth Olsen, as she navigates through fame swell.

She explained: ''I was not caring what I was saying [in interviews] because I'd assumed no one would read it. That's when we'd have conversations. [Mary-Kate and Ashley] would say, 'You know, even if you don't think anyone's going to read this article, someone might pull the quote later for [something else].' It's all part of how you hope someone interprets you, and how they frame who you are and the work you do. They're very tight-lipped - notoriously so.''