I don't remember having special interests as a kid.
One thing that always drove me nuts when filling out job applications was that they wanted me to list my talents and hobbies. One of the only times in my life that I've told a bold-faced lie was during a job interview at age 17 for a fast-food restaurant when I told the supervisor that I could sing. She asked me to tell her about hobbies and talents, and I had NONE. I was obsessed with Stevie Nicks, though, for some unfathomable reason, and sang along with the records, so I said I could sing. Why I need a "talent or hobby" to work at KFC, I can't begin to imagine. (I didn't get the job, thank God.)
My special interest is daydreaming about my favorite actor, but there's not much of a hobby there! If I lived alone, I'd put a pictures of him all over my wall, and watch his movies more often than I do, but we already have one aspie in the family who inflicts his special interest on everyone else, so I just keep it all in my head.
For the first time in my life I do have a couple of hobbies, and I tend to get wrapped up in them and forget to do the laundry or take the chicken out of the freezer, but I never thought of them as AS things. One of them is knitting. I recently learned, and I suppose I get a little weird about it. Another is making Lego movies, but I haven't been able to work on that lately. Once I get into it, though, I'm REALLY into it. The thing is, though, up until recently, I had no time for hobbies. At this point in my life, I do have a bit more free time than I used to, although it means neglecting housework. In early adulthood, I had no space or money for any hobby that involved actually doing anything.