Even ignoring my other thread where I gave links to Realm of Chaos: The Lost and The Damned, Lexicanum cites the book for the shaman origin.
Realm of Chaos: The Lost and The Damned is cited for the shaman origin at the bottom of the Emperor's Lexicanum page with the other cited sources. I have Realm of Chaos: Slaves to Darkness and Realm of Chaos: The Lost and The Damned as Christmas presents. I saw someone named Prince Endymion on here say the shaman origin is a theory that was not published anywhere at all. If he is still here, then I take it you haven't followed 40k since 1st Edition Rogue Trader or own stuff from the first edition of 40k? Its alright. But do your research (if you are still here) before saying that. The lore of 1st Edition Rogue Trader was awesome.
https://www.ebay.co.uk/itm/WARHAMME...F-CHAOS-THE-LOST-AND-THE-DAMNED-/382270144333
https://www.amazon.com/Warhammer-40-000-Rogue-Trader/dp/1869893239
https://spikeybits.com/2018/01/nurgles-lost-the-damned-realms-of-chaos.html
https://spikeybits.com/2018/01/nurgles-lost-the-damned-realms-of-chaos.html
http://www.belloflostsouls.net/2014/06/40k-retro-corner-realm-of-chaos-lost-and-the-damned.html
Realm of Chaos: The Lost and The Damned is cited for the shaman origin at the bottom of the Emperor's Lexicanum page with the other cited sources. I have Realm of Chaos: Slaves to Darkness and Realm of Chaos: The Lost and The Damned as Christmas presents. I saw someone named Prince Endymion on here say the shaman origin is a theory that was not published anywhere at all. If he is still here, then I take it you haven't followed 40k since 1st Edition Rogue Trader or own stuff from the first edition of 40k? Its alright. But do your research (if you are still here) before saying that. The lore of 1st Edition Rogue Trader was awesome.
https://www.ebay.co.uk/itm/WARHAMME...F-CHAOS-THE-LOST-AND-THE-DAMNED-/382270144333
https://www.amazon.com/Warhammer-40-000-Rogue-Trader/dp/1869893239
https://spikeybits.com/2018/01/nurgles-lost-the-damned-realms-of-chaos.html
https://spikeybits.com/2018/01/nurgles-lost-the-damned-realms-of-chaos.html
http://www.belloflostsouls.net/2014/06/40k-retro-corner-realm-of-chaos-lost-and-the-damned.html