I went to the Alps in August because my son — a New York City third grader obsessed with baseball, projectiles and YouTube — fell in love this summer with the Swiss children’s novel “Heidi.”

OK, we were going to Switzerland anyway to visit his aunt and uncle in Geneva. And I was the one who introduced my son, R, to the novel, after Googling “kids books switzerland” one night before our trip. But I never expected it to be a hit. I certainly didn’t expect to find myself weeks later in an Alpine enclave called Heidiland, wandering with my 8-year-old superfan through the knot of trails and villages that inspired the story.

“Heidi,” published in 1881 by Johanna Spyri, is the three-toed sloth of children’s books; it moves so slowly, with such little action, that whole ecosystems could flourish undisturbed between its pages. The titular character is an orphan who lives with her misanthropic grandfather and their goats in the Swiss Alps. At 8, Heidi goes to a big foreign city (Frankfurt) to stay with her wheelchair-using cousin, Clara, but grows restless and returns to the mountains. There, through Heidi’s ministrations, her grandfather finds God and re-enters society.

I started reading my son a free online version at bedtime, mostly for its lovely descriptions of the Swiss landscape. I figured he’d tolerate five minutes, tops. Instead, R made me keep reading until my throat was raw. By week’s end, he had acquired a library copy and was poring over it each night in the tiny oblong glow of his bedside LED.

I was thrilled, of course, but baffled. R was no bookworm; until recently, he’d struggled with reading. And I couldn’t work out how a boy who thrived on armed combat and poop jokes had fallen so hard for a tale of pastoral youth and spiritual transformation. It felt almost like spite.

Like many parents, I have tried to pass on the highlights of my early reading life to my children (R and his little sister). And, like many parents, I have been crushed when the box sets of serial mysteries and Beverly Cleary paperbacks I buy with aching affection remain untouched. Children are not miniature versions of yourself. They do not like what you like, or what you think they will like. No matter how many times this has been demonstrated to me over the years, I’m always pancaked when the reminder comes.