In the Unremembered Empire, Guilliman muses on the fact that both the coincidences of the various Primarchs home worlds and how they suited that Primarch so well and The Emperor himself are too perfect to have been coincidences and The Emperor being the perfect being that he is would have had the foresight to want battle tested and forged generals rather than cookie cutter officers, but I have my own separate theory about Guilliman having Aspergers so take that with a grain of salt.

As far as the Terran marines being concerned, the rune priest, "Longfang," was a Terran, one of the last and one of the oldest, in Prospero Burns and he was subject to the effects of the Canis Helix, being long in the fang and the yellowing of the eyes and hardening of the skin. The Horus Heresy Book 3: Extermination also mentions that, along with the Salamanders and Alpha Legion, the Space Wolves were part of a secret project called the Trefoil that further differentiated them from the other legions. Also, somewhere someone responded to "There are no wolves on Fenris," with "Because they're all in space," but I can't recall who.