fred2
Where'd That 6th Toe Come From?
The thing is though, retcons happen all the time, and not just to Fallout. It's the one problem with fictional universes in general; their histories are always subject to minor (or major) changes depending on the stories that the writers want to tell. To have a fictional universe free of retcons, you'll need to either stifle any sort of creativity going forward, avoid doing sequels, plan out every last minute detail of backstory yourself (thereby effecting option one) -- which could quite possibly take many, many years -- or any combination of the above. Either way, retcons keep the series going and evolving from a story standpoint.
Indeed. This was most notable with Beth reboot that for obvious reasons was separated from the originals.