Mary-Kate and Ashley Olsen "share" memories.
The 24-year-old twins - who shot to fame after appearing in US TV show 'Full House' aged just nine months - have such a close bond, they struggle to separate particular incidents in their past and work out who actually experienced them.
Mary-Kate said: "Some of our memories are shared. We don't know what actually happened to whom. One of us was stung by a bee, but we can't remember who, because we both felt it."
The pair - who currently work together on their fashion line The Row - also revealed they share outfits with one another as they can't always establish ownership of a particular garment.
Recalling her younger days, Ashley told America's Vogue magazine: "I'd go through my closet all the time, putting things together-it looked like a tornado hit it. Still does.
"How do we divide clothes? There's hers, there's mine. And a huge 'maybe' pile."
Despite their achievements in fashion, TV and film, the twins still have "big" plans for the future, with Ashley expressing a desire to make even more of a success from the business side of her career.
She said: "I want to run a studio. I'd probably like to manage other people on their brands. It could be an artist. A young designer. It could be an existing brand."
Mary-Kate added: "The thing about us is we think big. Huge."