Board Thread:Warhammer 40k General Discussion/@comment-72.93.49.215-20140912200020/@comment-6078851-20140913143426

i'm not sure about pre-heresy but the dark angels have the purest gene-seed (least mutated) of any chapter, and ultramarines are second (i think). the dark angels codex mentions this and that the inquisition's gene-seed people (dunno what that branch is called, 'gene-seed administration board' or something :P) are the only people who know that D.A gene-seed purity surpasses any other chapter - despite their arrogance in their chapter's superiority even the D.A's inner circle doesn't know this.