My fear of cockroaches is deeply rooted a childhood incident. It has followed me since.
But to be honest, I was afraid of a lot of crazy stuff as a kid. I was afraid of noise from planes and drills. Now I never notice the planes , and the drill is just annoying.
Hey, how about something you didn’t fear as a kid but do now? In my house there is a small storage room. When I was young the room was equipped with a light, and it was actively used for storing stuff, so it was just a weird but fun place to hang around and play hide-and-seek. Then we moved things out elsewhere, the light got broken, and the only thing left in the room is the main power supply of the house. That room is now a thing from nightmare itself. You don’t know what’s inside in because you can’t see anything, and there’s the obvious risk of being electrocuted.