Pardon my poor taste above. I get pretty wound up now and then.
Mathematic considerations apply to trying to have kids, for me. More multivariable calculus, in fact, than youve probably ever used before in real life, unless youre an engineer. Just kidding, it is extremely simple.
I'll assume for the sake of speculation that our new friend the X factor turns out to have the same transmission HIV does, so that my putative offspring neednt worry about all that. He can just marry another patient, there are plenty of em about.
The risk of debility, poor quality of life, remains. But one kind of debility is just as good (bad) as another, to a large extent. Suppose XMRV causes CFS, there is some vertical transmission, and the right interventions get it down to 1%, which is none too dissimilar to what happened with HIV. All that is science fiction at this point, of course.
Further, posit that treatment is only 70% effective so that some misfortune still applies to someone that got the virus vertically. I would find this risk acceptable. The reason is because there is already a significant body of risk, so adding this risk does not really change things by more than, say 10-20%. For example, the lifetime risk of schizophrenia (or of any incurable disease) is roughly the same as its point prevalence, in schizophrenia's case about 1%. Thats high, far higher I think than most people would guess. Multiple sclerosis, ~0.2% as I recall. There are some rather benign cases, but most arent, I think. Epilepsy also ~1%; I'm not sure how many cases of it result in poor life quality. Some certainly do. Birth defects. Severe chronic depression. Accidents. One could go on. I'm not counting things that would largely afflict a person above 60, since decrepitude and death at such ages are certainly "fair", insofar as illness and mortality are fair at all.
The chances of life being bad are rather imposing, and CFS is only a sliver of this. Even beyond debility, there is a lot of carnage and upheaval in this world that is just plain death. In my country, a stunning two million+ people have been killed by cars, four times the number killed in battle in the 20th C., which amounts to a lifetime fatality risk of ~1% (a bit above 1, I believe). I have no idea how many survivors of accidents are maimed, or (what is generally worse) have chronic pain.
Merry Christmas! I still drive a car, of course. But I stick to speeds around the 5th percentile, much to the chagrin of my fellow townsmen.