User blog comment:Supahbadmarine/Too Many Loyalists!/@comment-1932673-20110606150904/@comment-1932673-20110607151211

Tardir, what you have just mentioned is actually more or less the example of anti-canon on the rules page. LOL!

Plus the lost primarchs were either so faulty or committed acts so heretical that the Emperor had them destroyed and forgotten even before the Heresy, indicating that they committed a sin even worse then Horus, meaning any of their geneseed would have been destroyed, and even if it did exist, the Imperium would never use it, since that would worse then using traitor geneseed. Also back to Supah's point if the BR are founded from the TS geneseed (most likely between the 3rd and Dark Foundings) then it would then have had to have been modified to ensure genetic stability, so it would no longer truly be TS geneseed. An other explaination for the genetic traits of the BR is that they are descended from the Grey Knights, which is alltogether possible, given they have many psykers, yet genetically stable and they don't know their primarch and no records are kept of their founding, meaning it is alltogether feassible they were created during the Dark Founding, or another founding with a fair number of missing records (which too is feasible since many of the foundings aren't detailed by GW.