By Emily Willingham, science editor at the Thinking Person’s Guide to Autism.

You might have learned somewhere that autistic people tend to have obsessions. Back when my oldest son, TH, was diagnosed with autism, the clinician types called them “unifocal obsessions.” They’re some target of attention that was unusual for the child’s age or developmental stage or just flat-out weird. Often, writers or TV shows will give examples of these unwavering interests, with trains or dinosaurs usually topping a list. What’s funny to me is that if you obsess about these things as a child, it’s considered strange. But if you do it as an adult, you’re what we call a “professor.”

What you might not see on such lists is the enormous range of interests that autistic people can have. I took a quick Facebook poll of autistic people and autism parents for this post, just to get some specific examples. Among the many replies: cooking, catalogues, Blues Clues, gymnastics, Devo (yes, the band), Mario, US presidents, insects, LEGO, Minecraft, logos, music, antique surgical instruments, maps, old drum machines, astronomy, elevators, receipts, medical equipment, and sea turtles.

In our case, our son’s major, lifelong obsession is acorns. He’s basically a human version of Scrat from the Ice Age movies, and, like Scrat, thinks that heaven should be paved and furnished with acorns. Since he was a toddler, he’s loved this little fruit of the oak tree and is still a kid who yells out “acorns!!!” with the kind of excitement children usually reserve for spotting the ice cream truck.

Another part of the “autism obsession” cliché is that autistic people, once you get them rolling on their subject of interest, will not stop talking about it if they’re speaking autistics. We’ve never had that with our son and acorns. In fact, our son might know the genus for oak tree, but I’m not sure because he doesn’t talk endlessly about acorns if someone brings them up. (OK, I just asked him, and he does know the genus; it’s Quercus. He actually knows quite a few common names for oaks, especially the burr oak, which makes acorns the size of ping-pong balls, swallowed in their enormous, fuzzy hats that look like tiny thatched roofs. Even if you’re not an acorn fan, burr oak acorns tend to astonish.)

But my son’s obsession turns more to the visual and the acquisitive. He’ll look at an acorn for long periods of time. One single acorn. He names them—the most recent was called “Edward.” We don’t know anyone named Edward, except for that acorn. He sleeps with them. He asks for them for Christmas. When he can, he collects them by the dozens and creates elaborate, swirling designs on the floor or ground with them, which he then requests that we document photographically.

Acorns are everywhere in our lives—under feet, in the washing machine, in the crannies of our minivan (aware of oak disease, I try hard to clean these out) and under mattresses. We have books about acorns and acorn holiday ornaments. Acorns have soothed our son’s social anxiety, making him able to enter a classroom, and they’ve served as a reward to hold out for a job well done. Like Scrat, our son is happiest when he’s around these little tree nuts and that makes us happy, too.

Are acorns his only interest? No. He loves Pokemon, chess, maps, all things about the natural world, mythology, and the periodic table of elements. All of those focused interests share the commonality of underlying order and rules and organization. But an acorn? Well that that tiny seed holds all the instructions for becoming an oak tree. And there, the rules end. The rest is a matter of the right mix of nurturing and leaving the way open to potential. Similarly, our son arrived in this world programmed to grow and develop as a human. But there, the rules end, too, and not a day goes by that he doesn’t show us the benefit of leaving him space to find his potential, and that includes space for the things he enjoys most.

Have (or know) an autistic child with an interesting passion? Post a comment and tell us about it here!

Emily Willingham is science editor at the Thinking Person’s Guide to Autism and managing editor at Double X Science, an online science magazine for women.