“Life is incredibly complex, there are lots of things going on in our environment and in our lives at all times, and in order to hold onto our experience, we need to make meaning out of it,” Adler says. “The way we do that is by structuring our lives into stories.”

It’s hardly a simple undertaking. People contain multitudes, and by multitudes, I mean libraries. Someone might have an overarching narrative for her whole life, and different narratives for different realms of her life—career, romance, family, faith. She might have narratives within each realm that intersect, diverge, or contradict each other, all of them filled with the micro-stories of specific events. And to truly make a life story, she’ll need to do what researchers call “autobiographical reasoning” about the events—“identifying lessons learned or insights gained in life experiences, marking development or growth through sequences of scenes, and showing how specific life episodes illustrate enduring truths about the self,” McAdams and Manczak write.

If you really like James Joyce, it might be a lot like James Joyce. People take the stories that surround them—fictional tales, news articles, apocryphal family anecdotes—then identify with them and borrow from them while fashioning their own self-conceptions. It’s a Möbius strip: Stories are life, life is stories.

People aren’t writing their life stories from birth, though. The ability to create a life narrative takes a little while to come online—the development process gives priority to things like walking, talking, and object permanence. Young children can tell stories about isolated events, with guidance, and much of adolescence is dedicated to learning “what goes in a story… and what makes a good story in the first place,” Pasupathi says. “I don’t know how much time you’ve spent around little kids, but they really don’t understand that. I have a child who can really take an hour to tell you about Minecraft.” Through friends, family, and fiction, children learn what others consider to be good storytelling—and that being able to spin a good yarn has social value.

It’s in the late teens and early years of adulthood that story construction really picks up—because by then people have developed some of the cognitive tools they need to create a coherent life story. These include causal coherence—the ability to describe how one event led to another—and thematic coherence—the ability to identify overarching values and motifs that recur throughout the story. In a study analyzing the life stories of 8-, 12-, 16-, and 20-year-olds, these kinds of coherence were found to increase with age. As the life story enters its last chapters, it may become more set in stone. In one study by McLean, older adults had more thematic coherence, and told more stories about stability, while young adults tended to tell more stories about change.