Since everyone must eat, what we eat becomes a most powerful symbol of who we are. To set yourself apart from others by what you will and will not eat is a social barrier almost as powerful as the incest taboo, which tells us with whom we may or may not have sex.
Some cultures equate the two taboos.
Margaret Mead quotes a New Guinea proverb that goes, Your own mother, your own sister, your own pigs, your own yams which you have piled up, you may not eat. Own food, like related women, is for exchange, for gift giving, for social generosity, for forging alliances, but not for personal consumption. The obverse of this is that you identify yourself with others by eating the same things in the same way. To achieve such identification, people will struggle to eat things they loath, and avoid perfectly tasty food that is on the forbidden list. In the process of social climbing people have to learn to like caviar, artichokes, snails, and asparagus, and scorn dumplings, fish and chips, and meat and potato pie all more nutritious, but fatally tainted with lower-class associations.