All this self-infantilizing, of course, has everything to do with the main difference between us Rejuveniles and, say, African farmworkers: We are wealthy and idle enough to delay adulthood, or even, god forbid, write posts on the Internet about the onset of adulthood.

Further contributors to the confusion: We have this wealth but lack any unifying customs. We don't have something like a toga virilis, the chalk-white robe Romans wore to mark manhood after it was time to offer their childhood amulets up to household gods. A suit and tie is a close approximation, I suppose, whether you're the managing director of Bain Capital or a shift manager at Applebee's. But still, for those of us who eschew Jewish or Wiccan or Catholic rites of passage, and who don't have to get dressed to work, it's up to us to define what manhood is and when it happens.

And on that score, I have no answers. I wake, I eat, I try not to lose my temper at my lovely children, and then I travel for work to places where I'm absolutely sandblasted by the miseries and occasional joys of others. Life is full and enervating and confusing enough without trying to wedge a definition of manhood into it. Case in point: on the nearly 16-hour flight back to New York from South Africa, I spent some time going through my notes, and even more time playing a boxing game on my iPhone. Does that make me a child? A man-child? A rejuvenile? I don't know. But when the dinner cart finally made it to the back of the plane where I sat, I ordered the chicken, whether or not I deserved it.

–Nathan

One recent Monday morning, I was telling a co-worker about my weekend: There had been a playdate with my daughter, Sasha, and one of her friends, and I'd been having some trouble with my apartment's hot-water heater, and I'd gone shopping at the farmers' market for vegetables for the week. All in all, nothing special. Just a typical Brooklyn weekend.

But for my co-worker, this was amazing. "You're a real grown-up!" she said.

I wasn't quite sure what to say. I'm still relatively new to the working world. After freelancing for the last eight years, I've only just taken a full-time job—and it's one where I'm at least a decade older than almost everyone on my team. At the age of 38, married, with kids, a mortgage, a beard, and a receding hairline, I suppose I must really seem like an adult to them.

If only I seemed like that to myself! Though I never wanted to be one of those much-derided man-children loafing around Brooklyn coffee shops—"grups," New York magazine dubbed them—I was never all that eager to embrace the traditional outward markers of adulthood: suit and tie, office job, lightless dead eyes. And in truth, I'd always felt like a child. The sense of smallness and powerlessness that are a child's everyday experience had never fully left me. When I'd look at my own father, a tenured history professor, I could never imagine becoming like him. And when I looked at kids, I felt nothing but sympathy—I know what you're going through—and imagined they were looking at me and thinking, Dude, you look older, but I see through you; you're just like me.