In December 2005, the novelist and short story writer A.M. Homes (The End of Alice, The Safety of Objects) published a personal essay in The New Yorker about how, more than a decade earlier, the birth mother she never knew began trying to seek her out. Events did not proceed happily: The woman stalked Homes at book signings and called her apartment repeatedly, begging her daughter to allow her into her life; the birth father wanted nothing to do with the situation; Homes felt her own life quickly slipping out of her control.

The author recounted all of this in crisp, clipped, almost Joan Didion-like prose—the article read as if it had been written in a state of shell shock. The style only strengthened the central theme of the work: Namely that, with just a single phone call, our lives can be immediately, irrevocably plunged into confusion and existential despair. Deep down, none of us “really” knows who we are.

Homes’ New Yorker article has been expanded into a book-length memoir, The Mistress’s Daughter. Despite a few missteps, it proves even more affecting and illuminating than the magazine piece. Beginning a few days before Christmas in 1992, when Homes’ adoptive parents sit her down to tell her “Someone is looking for you,” the book charts an often sad, sometimes spooky journey. Homes had long known that she was adopted, but she never fully understood the details about who her birth parents were. The fact that this mysterious, possibly unstable woman named Ellen wants to insert herself into Homes’ life shakes the author to her core.

But—probably like many adopted children once they enter early adulthood—Homes soon becomes obsessed with reclaiming the identity she never really knew. She reaches out to her birth father, Norman, a former college football player who’s now a successful businessman with a family of his own. First, he seems to want to get to know her, but soon he grows suspicious and even vindictive—demanding a DNA test, the results of which he refuses to report to her.

Later, Homes gets drawn into the world of genealogical research, spending months trying to trace her family background. For reasons even she doesn’t entirely understand, she becomes determined to join the Daughters of the American Revolution—something she can only do if Norman is willing to hand over those DNA results.

Homes’ fiction sometimes comes off as a little too studied and willfully quirky, but here she’s speaking straight from the heart, and the story’s strange twists feel completely organic—the actions of a complex, tortured main character. Some of the passages carry on too long, including a section where Homes takes an inventory of her birth mother’s belongings (Ellen died in 1998); and one of the chapters—in which Homes imagines Norman being legally deposed, because she’s thinking of suing him to prove his paternity—is entirely ill-conceived, a Creative Writing 101 stunt that should have been cut from the book.

But the triumph of The Mistress’s Daughter is that it never turns parochial or self-absorbed, despite the specificity of Homes’ story, and despite her novelistic tendencies to wax philosophic about mundane, probably meaningless details, like the list of prescription drugs Ellen took before her death. Homes draws out the universality of her own experience. She shows us that—whether we were adopted or not—we can never possibly understand where we’re headed if we don’t first figure out where we’ve come from.