/// Ogres were people who hunted and ate other people in the Darkness, and came to enjoy it, and grew powerful on this. Perhaps they wer inspired by the cacodemon, perhaps it manifested as their power grew. Today, they can still "intiate" evil humans into ogredom by partaking their horrible meals with them. It is well known the lunar empire builds legions of strong, fast ogres by feeding reluctant war prisonners to other, compliant prisonners.
I'm not aware of any reference that cannibalism turns you into an Ogre.
There are a number of species (Uz) and cultures (Cannibal Cult) in
glorantha that practice cannibalism but are not Ogres. While gloranthans
may believe that Cannibalism turns you into an Ogre, I haven't see any
hard evidence of a person become an Ogre through cannibalism.
--Peter Metcalfe