[thedoc (OP)]

Benjamin Robertson asked the Naked Scientists:
   Why is it that the taste of some food can make one person gag, or dry heave, while another person can have no response at all? For some people the food that makes them gag has no overwhelming taste of sourness or bitterness, or any other taste which I usually associate with a possible gag reflex. Is this mostly psychological or is there an evolutionary reason behind the gag reflex?
What do you think?

[evan_au]

It could be due to a bad reaction in the past (eg food poisoning or allergic reaction), which has left them with a bad association.

I imagine that remembering a bad association could protect you in the future - although sometimes it will cause a false alert, as the bad reaction may have been due to unrelated causes.

Sometimes avoiding a good food is probably safer than repeatedly trying a bad food!