That response to the bite sounds exactly like my progression from normal response to near-immunity. As I mentioned above, it's not like I've always been immune

That response to the bite sounds exactly like my progression from normal response to near-immunity. As I mentioned above, it's not like I've always been immune and there wasn't one day when suddenly I became immune. Its been a long multi-decade process (I'm 31 now). In my early twenties, I would itch and welt from a mosquito bite for maybe 10 minutes. Now, I don't welt or itch. When I was in my early teens, it was probably more like an hour of welt + itch. I'm fascinated by bugs. I've always let them bite me for a while (even when I knew they would itch later). The joy of observing them always outweighed the itch for me. I think it's only because I've always let them bite me that I was able to get a sense of how the itching and welting changed over time. In retrospect, I wish I had kept detailed records of the timing change.