As someone who gets a wicked cold sore every year I always hate hearing about stuff like this. It's terrifying what can happen to babies if you kiss them with HSV-1.
My wife has oral HSV. I don't. We're not careful and we've been together for years with many breakouts. I don't think I've avoided it because I'm magically immune. My guess is that I have it, but I managed to limit it to the degree that I never get a breakout.
Now that I think about it, my wife hasn't had a breakout in two years, pretty much since getting pregnant. Weird.
During pregnancy the mothers immune system is muted, which prevents "rejection" of the fetus.
However, in an almost "parting gift" fashion, the departing fetus actually leaves behind immune cells that can provide years of boosted immune activity.
I know I’ve been exposed countless times from similar experiences, and have always (100% of the time, n==10ish by now) tested negative for it.
Is that so weird? With how prevalent it is, I don’t see how it’s actually possible for <100% of people to not have it otherwise. Unless some large percentage of people are literally living in a bubble, anyway.