I am not old enough to remember 9/11. But it matters that I carry on the memories of others.

On a sunny July weekend, I visited the 9/11 Memorial & Museum for the first time. I was with Robert, a friend who had grown up in New York, and he said that I needed to see it.

We stood there quietly for a while, palms on the cool marble, watching the water cascade down and the tourists take photos. Robert told me about what that morning had been like for him and his family—where he had been, what he had felt.

Though Robert and I are close in age, his experience of the terrorist attacks of Sept. 11, 2001, is dramatically different from my own. He is a few years older than I am—in 2001 I was only 2 years old, not old enough to have memories of my own of the day. Nor can I ever fully understand what that day was like for children who grew up in New York in the wake of the attacks. It was moving for me to be invited into Robert’s perspective during the afternoon when we visited the 9/11 memorial together.

Although Robert’s experience of Sept. 11 and my own are in many ways dissimilar, we have both come of age in an American society defined by that day. While I cannot remember 9/11 itself, it has deeply shaped my generation. The day is woven into the fabric of my life and the lives of everyone I know. I have no memories of a United States unmarked by terrorism, and I have grown up in a world struggling to come to terms with the scale of such violence.

The day is woven into the fabric of my life and the lives of everyone I know. I have no memories of a United States unmarked by terrorism.

When I think of what it means to commemorate the attacks and to honor the lives of the Americans who died, I think of the tensions in my own remembering.

I am the third of four sisters: My two older sisters, who were 7 and 5 years old at the time, remember 9/11, while my younger sister and I do not. The day is part of my family’s collective memory, but not my own. I have grown up negotiating this grey area between personal and collective remembering.

When I look at our family photo album of 2001, the year that my younger sister Molly was born, it is shadowed by the events of Sept. 11. On one page of the album, photos from Sept. 9 show a priest baptizing Molly in my family’s living room, with me and my sisters cooing over her bassinet. In the next page’s photos, my older sisters stand in the front yard, looking confused and somber, clutching candles for a vigil on an evening following the attacks. Turn another page and it is Halloween, and my sister Rose is dressed as a firefighter—all the neighborhood children had been told to wear costumes evoking goodness and heroism.

Throughout my childhood, I looked at these photos—scenes I was present for, but which I could not remember—and I have wondered how to make sense of this dividing line in my sisters’ and my experiences, how differently 9/11 inhabits our emotional landscapes.

It feels like the memories of the adults around me slipped into my bloodstream, my memory, in airport security lines and at annual prayer services. Sept. 11 has always been part of my consciousness.

For much of my life, the events of Sept. 11 have been an indistinct blur of emotion and image and story, never really taught to me, because how could they have been? It was part of our lives, after all. The stories did not belong on the pages of history textbooks because they were still on every American’s lips. My job was to listen as they told the stories to me: where loved ones were when they heard the news. The fear, the confusion, the grief. What people said, how they felt, whom they called first. It feels like the memories of the adults around me slipped into my bloodstream, my memory, in airport security lines and at annual prayer services. Sept. 11 has always been part of my consciousness.

But as I enter adulthood, I feel the need to more intentionally consider how people my age are stewards of these memories. Twenty years later, what does it mean to remember 9/11?

I study history at the University of Notre Dame, where my professors discuss the critical turning point when an event shifts from residing in living memory to residing in historical memory. Essentially, this shift occurs when the window closes in which you can hear about an event directly from those who experienced it. After an event moves totally into historical memory, no new primary sources will be created, no new oral histories are possible. Historians have to rely wholly on archives.

My generation inhabits a grey area, with one foot in living memory and the other in historical memory, as it were. Everyone older than me holds 9/11 as part of their lives, while everyone younger will learn it as history. Twenty years after the event, all those with personal memories of 9/11 have entered adulthood, and how we remember it matters—not only for those directly affected by the tragedy, but also for all those growing up with only secondhand knowledge of this American story.

Passing on what we know and feel about this chapter in American history—not letting our loved ones’ stories disappear—is a sacred task.

Memory and history are not passive or objective processes. We can learn a great deal about what our society values from what is recorded, what is silenced and what is simply forgotten. My perspective as a history student makes me feel as though people my age have inherited a responsibility to others’ memories of 9/11, to which we are so proximate. Passing on what we know and feel about this chapter in American history—not letting our loved ones’ stories disappear—is a sacred task.

After 20 years, 9/11 is widely discussed less as memory and increasingly as history. Collectively, Americans are at a turning point much like the grey area into which people my age were born. How we memorialize 9/11 at this juncture matters: It will help define what is passed on to those who will learn about 9/11 only as history.

The memories of 9/11 have been passed on to me since I was old enough to remember. As we mark the 20th anniversary, the stories we share and the memories we keep matter. I do not have good answers to the questions of how best to memorialize 9/11, how to pass on the stories to those further removed from this past. Nor do I feel like a qualified narrator of this chapter in our collective memory—there is a tension in having lived on that day and yet inherited my emotions and words for it through others’ lenses.

Nevertheless, I hold onto the history I inhabit: my sisters’ memories of their grade school classrooms that morning, my mother recounting the phone calls she made, the juxtaposition of photos in my family’s album, the stories Robert shared as we watched the waterfalls of the memorial.

People my age are privileged to stand in the interstitial space between living memory and historical memory. Imperfect storytellers though we may be, it is our responsibility to hold onto what we have been given: to carry the memories of our common past and to honor those in our lives who shared those memories with us, making them, in a way, ours.