I'm telling you, the Bosmer are direct descendants to the Aldmer. It clearly states this in lore.
The source I read said otherwise, BUT, Beth puts more time into biasing and creating falsehoods among in-game books than they get credit for. Example: Ursinethropes. They are supposed to be ALL over Skyrim according to some [censored] with a paper and a pen, but they obviously aren't.
To be honest, I find the Bosmer disgusting and bizarre and only know of them what pops up in other races lore.