So, Asterion has an aversion to cow milk. Now this could go with the trauma from the cannibalism accusation, even though it's not since the purpose of milk is to feed the infants of that species. Most of us were likely fed human milk in our earlier years too. Another possibility is that most mammals, will forego of milk permanently once they are old enough. This also goes with there not being human milk for sale, be it innapropriate to our cultures or just not readily available. The question here is what exactly is the matter that has Asterion avoiding it? Cannibalism? Outgrown it? Against "his" culture? Would it be a kinky sex thing?