After thinking a little bit, the very first interest I can remember was probably the alphabet, when I was 2. I remember looking at books and TV writing and I tried as hard as I could decoding all kinds of writing. It was successful. 1 year after, I knew how to read and I started writing, and I also started math the same way, by using a calculator. I still deeply enjoy any kind of decoding now, with a preference for computer programming. I can spend hours looking at scripts to understand how they're made by myself.
Other than that, my biggest fascination was robots. All kinds of robots. As long as I can remember, even when I was a toddler, I've always had the same kind of reaction to robots : "wow !" Even now.
I've always been fascinated by flying, space exploration, planes... Astronomy, the Big Bang...
Biology and geology too. Evolution, dinosaurs ; volcanoes, minerals...