User blog comment:Supahbadmarine/Too Many Loyalists!/@comment-1932673-20110606150904/@comment-9734625-20110606221851

Yeah. Just because mixed Gene-Seed isn't directly mentioned in Canon, it might as well be canon. And about the Blood Ravens: There is also a possibility that they have a connection to one of the Lost Primarchs. What if the BR have mixed geneseed from one of the Lost Primarchs and added Thousand Sons, or that the Thousand Sons are mistaken, and that the BR are one of the 20 Original Legions? It is all an enigma, untill GW, quote, "gets their finger out of their arse". I say that we should allow Gene-Seed mixes until something is said by GW about the matter.