What can twins teach us about human nature and personal identity? One author explains

For '90s kids, Mary-Kate and Ashley Olsen were the dominant force in twin fiction. Over the years, other generations have been fascinated by characters like Wrigley's Doublemint Twins, or Hayley Mills and Lindsay Lohan in the 1961 and 1998 versions of the film "The Parent Trap," respectively.

Twins are rich narrative terrain and raise questions about individuality.

"They're a natural kind of hook for a bunch of questions about human life in general," said Helena de Bres, a professor at Wellesley College and author of "How to Be Multiple: The Philosophy of Twins."

Her identical twin, Julia de Bres, illustrated the book. Together, they explored the twin experience through a philosophical lens and examined free will, love, and personal identity.

"I think people are fascinated because we're just kind of cute and unusual and trippy, but also because we raise these really big questions just by standing there," Helena de Bres said.

Stories about twins go back to antiquity: Castor and Pollux, Romulus and Remus, and Hercules and Iphicles all represent binaries that describe human nature.

"You can use twins narratively to explore a whole range of different contrasts, or different ways of living or being," Helena de Bres said. "So they're just really useful for getting at some of these questions. They're also easily used for comic purposes — you know, that whole switcheroo thing [of] twins switching places. Identity confusion is really ideal for theatrical treatments."

Whether twins fit neatly into those binaries is a different story. Helena de Bres said she believes that twin binaries are a created to differentiate between children who people can't tell apart.

"We're going to decide, maybe randomly, maybe on a little bit of a clue that this is the quiet one. And then the quiet one takes that up and starts acting into that role. And it is a self-fulfilling prophecy," she said.

Listen to Soundside’s full conversation with Helena de Bres by clicking the play icon at the top of this story.