Charles,
When my husband was diagnosed, I went through hell thinking that I was responsible for his illness. I had precancerous cells of the cervix 30 years ago (had the colposcopy and cryosurgery) and probably had one of the cancer-implicated HPV viruses, but nobody had ever heard of it back then. I expressed my concerns to a couple of Gordon's doctors who told me that it's impossible to say when/where he acquired the virus. Could have been me, could have been other partners. There's just no way of knowing. It's pointless to agonize about this. The virus is so common (although I'm not sure how common HPV 16 and 18 are) and there are so many other factors that come into play with developing cancer, you could drive yourself crazy trying to figure it out. You're right, you'll never know and it would serve no purpose if you did. I still feel terrible thinking that there is even a remote possibility that I might have given Gordon a virus that led to this dreadful disease.
Anne