I neither own things from the days of rogue trader nor have I ever played first edition (or second edition for that matter.) Not everyone has, in fact fewer and fewer people will have met either of those criteria when it comes to 40k. These days the shaman origin is hazy and seems to be a bit left in the dust by GW.
Are you Endymion? The shaman origin was printed in 1st Edition Rogue Trader.