In cultural and anthropological matters, outsiders have some advantages; habits peculiar to one culture may appear as "just normal and natural" to one living close to it.
As an example, and without straying from the topic, the Otomi Indians in Mexico who have magnificent teeth, described their own diet as entirely soft. Yet observation showed that they chew toasted haba beans of a hardness that makes it almost impossible for others to chew them. They also crack open nuts-a staple-with their teeth.