I have one leg, and my wife uses a wheelchair. I wrote a children's book to change the culture around intrusive questions people with disabilities are often asked.

• James Catchpole has one leg and has been asked about it for as long as he can remember.
• His wife has chronic pain, and their differing experiences inspired him to write a children's book. 
• This is his story, as told to writer Ashley Abramson.

This as-told-to essay is based on a conversation with James Catchpole. It has been edited for length and clarity.

I've pretty much always had one leg. Missing a limb makes you a walking question mark.

When I was a child, kids in the playground would ask what happened to me. I always felt it was my job to tell them. After all, adults often asked me the same question, so surely it was a reasonable one. I ended up writing a children's book called "What Happened to You?" about what it means to be asked this question. It took me 40 years to find the answer.

As I got older, I grew more uncomfortable sharing my medical history with strangers. Adults think they want to know, but it often turns out they don't — not when they realize it's a personal question with a difficult answer. It makes everyone awkward. And kids don't need to know what happened. They just need reassurance that, yes, some people have one leg, and that's fine. Disability is normal.

My wife, Lucy, also has a disability

I learned more about how people engage with disability when I met my wife. I was a student at Oxford when my cousin matchmade me with someone she knew, a recent graduate who just happened to have a disability, too. Lucy and I have been together for 19 years.

While we're both disabled, our experiences of disability are very different. As a through-hip, single-leg amputee, my appearance is dramatic. I have an artificial leg that I use in the house, but out in public, I get around on crutches. And when I say "get around," I mean "go fast": I used to run (I've slowed down now, but I still play soccer on my sticks). Back when we met, though, Lucy looked able-bodied — she could still walk when we met — but was very limited in her mobility and stamina by constant, severe pain.

So essentially, we were opposites. On the bus, little old ladies would jump up and offer me their spots, no matter how much I preferred to stand. In a bar, no one would give up their stool for Lucy, no matter how much she needed one. And when she was forced to explain her disability, she often wasn't believed. The contrast between our experiences made me think more consciously about the way the world responded to me. I started to question why people felt entitled to know.

Changing careers and becoming parents started a new chapter for us

I was thinking about a career in classical music, but with Lucy's worsening health, I began looking for work nearer to home. I took on a family business, my mother's literary agency, after Lucy and I married. I'd been helping out with the agency for years, reading the submissions and editing, so it felt natural to step into the role. And Lucy's degree was in English literature — she's much more well-read than I am. So the agency was a shared project, as was becoming parents.

We were worried in some ways about the logistics of having children, but whether we'd try was never really a question. I was always going to be the feeder, the diaper changer, the cook, and the cleaner. Lucy has to spend almost all her time in bed, but she's the teacher and comfort giver for our 4- and 8-year-old daughters. It's a different setup from many families', but for our girls, I think there's security in knowing just where their mother is all the time.

Taking our daughters to the playground reminded me of the questions children ask

Since my girls have a father with one leg and a mother who uses a wheelchair, disability is completely normal for them. (The bio on our Instagram account @thecatchpoles says, "More children than working legs.") But becoming a father meant going to playgrounds again, which reminded me of how relentless children can be when they see someone who looks disabled.

I was hearing the same questions I used to hear when I was a kid. A few years back, I started to answer children by saying, "What do you think happened?" My friend's son Casper asked me whether a burglar had stolen my leg. A kid at my daughter's school asked whether a lion had eaten it.

In a museum one day, a boy asked whether it had fallen off in the toilet. Turning the question back on kids was a neat way of deflecting it, plus their answers were always funny. And in the back of my mind, I was wondering whether there might be a story in all this.

I decided to write my own book on disability

As a literary agent, I've always received submissions for children's books written by parents of children with disabilities. These parents write about disability for the best of reasons because they want to see their children represented on the page. But none of the submissions ever rang true for me. It's hard to write about disability if you don't have firsthand experience.

Then I received one submission from an illustrator named Karen George, who hadn't intended to write about disability. But her main character was a one-legged teddy bear. I didn't take on her story, but I suggested we might collaborate on a new one that I could tell. She generously agreed.

Then it was time to pull it all together: my childhood memories of the playground, being asked that question again and again as I got older, meeting Lucy and seeing how people responded to her disability as opposed to mine, returning to the playground as a father with my own kids.

Because here's the thing: Being asked deeply personal questions by strangers — questions like "What happened to you?" and if you're a wheelchair user or have other visible differences, "What's wrong with you?" — can be one of the most difficult things disabled people face in their day-to-day lives. Those questions single you out, remind you of your difference, and demand you tell someone your most intimate, traumatic truths, just to satisfy their passing curiosity.

I wanted to write a book that showed readers how that feels from a disabled child's perspective. I wanted them to walk in Joe's shoe.

In "What Happened to You?" a boy named Joe is playing pirates at the playground, but children keep asking what happened to his leg. He doesn't feel like telling that story, and eventually, the children learn they don't need to know what happened and Joe's game looks more fun anyway. My hope is that both children and the adults who read to them learn that asking a disabled person to share their medical history is like asking a person why they're bald — only a bit more traumatic (I presume). Fundamentally, "What happened to you?" is a very personal question, and even children have to learn that we don't ask personal questions of people we don't know.

Having a visible disability might be like being a really low-level celebrity: none of the glamour but all of the stares. Writing my own story as a picture book with a cartoon version of me on the cover and seeing that book being read in schools and sold around the world in different languages — it feels cathartic. At last, I've been able to put my dramatic appearance to good use. It even gives me a very modest degree of actual celebrity, at least, in my daughters' eyes.