The Camoran dynasty was originally instated by the Aldmeri Dominion, we really only have the UESP's word for it that Haymon was a Bosmer, he could just as easily have been an Altmer or Ayleid (my personal favorite). While that wouldn't explain his Bosmer mother, the fact that Altmer are tall and Bethesda probably didn't want you looking down at the final villain does. Canonically speaking, he probably would have been a Bosmer.
That's a rather shaky asumption. At any rate, its still hard to prove he's related to them. Either way you look at it some guesswork has to be done along the way to tie them together. And so its just as easily possible Dagon had a hand in allowing him to ware the amulet. And even still it could have just been a developing oversite. Its just right now there's no solid facts dealing with the dragonborn without a "ya but" astric on the end.