“The Rumpus post helped me understand that no matter what I chose, there was going to be a loss,” Caliva said. Her ghost ship would either be a carefree life or the experience of parenthood. “That was freeing. It changed my perspective from having to make the right choice to just deciding.”

Caliva liked the column so much she sent it to several of her friends.

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The question of whether to have kids has puzzled me my entire adult life, in part because my reflexive reaction to the thought is “not again.”

There is a large age gap between me and my younger brother, and I was put in charge of minding him during many school breaks and holidays.

My brother was an easy-going preschooler. He pronounced “L”s as “W”s and wore a blanket like a Batman cape—the full “adorable kid” experience. Still, I was struck by how difficult it was to keep him entertained. I don’t possess the goofy sense of humor that charms the under-five crowd. I didn’t understand how to infuse excitement into otherwise boring activities like coloring or baking. We ended up watching a lot of TV, separately. I was so miserable that, one summer, I jumped at the chance to take a job filing papers in an office.

The experience of my teens left me feeling like parenting is, at worst, pure drudgery, and at best, feigning enthusiasm for someone who lacks a theory of mind. The problem is, I can’t tell if this is because 14-year-olds aren't meant to be full-time nannies or because I'm just not a kid person. And having one seems like a high-stakes way to find out.

Last fall, I posed the question—Why did you choose to have children?—on our reader blog, and the responses rolled in. In all my colleague Rosa Inocencio Smith and I collected and analyzed the emails from 42 readers, who were about evenly split between deciding to have kids and not to. (Caliva was one of them; she gave us permission to use her name and story.) To spoil the big takeaway, there doesn’t appear to be one “maternal instinct,” and not just because half of all pregnancies are unplanned. For some, parenthood is a hard-boiled belief; for others, it’s a switch that flips after a crisis. Other times, it’s just a feeling you get.

“People who’ve never had children seem really uptight about things that people with kids just roll with. Like, a little mess, or a muddy dog, or crumbs on the furniture,” wrote one mom named Mary. “A little softness in one's dealings is a pleasant aspiration. Kids do that to you.”

I was relieved to find that several people in the “no” camp described feeling perplexed by their peers’ drive to have babies: “It's like listening to people describe a color that I just can't see,” wrote Shanna.

The voluntarily childless do seem over-represented in our sample. Most American women—about 67 percent, according to a 2009 study by Ohio State University sociologist Sarah Hayford—decide as teenagers to have two children, and they roughly stick with that plan. Another, smaller group starts out wanting three or more kids and ends up having more than the average two; yet another segment starts out wanting two, but they wind up with fewer. Those like me are statistical freaks, making up just 4 percent of the population: We start out wanting kids … we guess? Maybe one? Our expectations decline with age, and, Hayford writes, “by their early 30s, these women expect to have no children.” (Her study was of women who were 18 in the 1980s; it’s not clear if the views of today’s women would evolve differently.)