when did I

I was thinking about what it means to like something, or what makes me like something. so the simplest model i have is this: if in my past, every time I do a certain action, or come across a certain object, I get some pleasure out of it, I become liking that thing or liking to do that action.
At home when I was very young, I was always the one who would volunteer to pick up dead cockroaches that sister killed. I would put a piece of toilet paper on it, and pick it up and throw it in to the toilet. I cannot remember when I stopped doing this, but all I know is that now, I am actually very afraid of touching insects - dead or alive. I don't even like touching plants, just in case something is crawling on it.
so surely there must have been a time when touching insects or similar things gave me constant horror, which makes me so afraid of them now. but I cannot find anywhere in my memory what that was...
I don't know whether I need to refine my model or I really am missing something in my history...