Ruth Ann Harnisch, a philanthropist with no biological children, takes it further: “Even though I’ve never been pregnant or adopted, it’s not in my soul that I have no children,” she told me. “Everybody’s child is everybody’s child. And I feel responsible for all kids as a resident of this planet.”

My friend Audrey, who died a few years ago, was a high school English teacher and poet who never married or had children, yet she found her way into the lives of scores of young people. She was not my teacher, but I inherited a relationship with her when I married one of her former students. After our divorce, Audrey was one of the few people we continued to share.

When she joined my book club, she was 25 years older than the rest of us, and provided another generation’s perspective during literary discussions. She had a surprising ease with us, maybe because she was used to being around much younger people. I have reminders of Audrey everywhere — a silk scarf from Thailand, a bulging envelope of handwritten notes and museum postcards.

Channeling Audrey, I’m collecting younger friends with a vengeance. Last year, as many of our peers were packing their children off to college, my husband and I traveled to Colombia and Jamaica for weddings of two much younger couples. In each case, we played the Audrey role, the friend who looks old enough to be the parent. After the Colombian wedding, we hosted a party for the newlyweds in our apartment. It was our gift to them and an excuse to spend more time with an energizing group of people.

As I was sorting all this out, I reread Meghan Daum’s 2014 essay in The New Yorker, “Difference Maker: The childless, the parentless, and the Central Sadness.” It’s an unvarnished account of her experience as a court-appointed advocate in the foster care system. She captured the yearning so many of us feel to influence or be of service to children even when they are not our own.

But the essay also captured the imperfection of it: “I was more like a random port in the unrelenting storm that was his life,” Ms. Daum wrote of her relationship with the boy she calls Matthew. The article helped me realize why I’ve made the choice I’ve made, to go where I think I can make a difference.

These days I spend a lot of my time with a nonprofit, Girls Write Now, which hits the trifecta of my passions: college access, empowering girls, and writing. I’m a relentless fund-raiser and evangelist for the group, and I do it for myself as much as for the girls.