The material borders of our tolerance to difference come through our taste buds. Merleau Ponty wrote:
In so far as I have hands, feet, a body, I sustain around me intentions which are not dependent upon my decisions and which affect my surroundings in a way which I do not choose. (1962: 440)
My way of reading this paragraph is: my perceptions, my inner states, the acuity of my senses, all are intrisically connected to my upbringing in and experience of this world. This is not very far away from what Foucalt (I think) meant by saying that power shapes us on a biological level, by shaping our needs and desires.
Coming back to difference and taste buds: my taste buds tell me what is 'good' food and what is not. My taste buds hate hot food; my taste buds cannot feel the flavor of curry. Closely working with my tastebuds, my sense of smell labels certain spices or smells as 'yakky'. Eating in certain ethnic restaurants or certain ethnic foods doesn't work for me.
And this is where my taste buds set the border of my tolerance to difference: I might know that living in another part of the world would have resulted in me liking to eat different things. But this rationalization doesn't help when I feel disgusted by certain smells or tastes.
On the other hand, my nose hates the smell of wine (alchool) and my taste buds hate the taste, which has nothing to do with culture, ethnicity or my close social millieu, since my parents and my friends always drank wine. There's no 'ethnic' element here. So why in some cases we label other people's food as 'ethnic' and as such a matter of good/ bad food, and in other cases it's simply a matter of acuity of senses?