Identity-based Ethics in Culture/Subculture Boundaries

Ethics, no mater how grounded in some mythical “virtue”, are culturally agreed upon. Call it a social contract if you like or just “common sense”, but either way, ethics are at their root an agreement. Some ethical agreements exist in a culture and all derivative sub-cultures. In Western culture this may be represented through norms regarding murder and suicide. Human life (because Western culture is a human-supremacist club) is considered to have some special intrinsic value, no mater how poorly lived the life or how much harm preserving the life could cause. Subcultures have variations in what is valued and what is considered ethical.

How do the ethical variations between a subculture and its parent culture interact? Is there a specific boundary-space where there is room for some form of mutual respect for ethical differences? Are the ethical desires of the parent culture to be imposed on the subculture despite their different values? Under what circumstances does a subculture gain enough legitimacy to have its ethical code respected? Is the cultural legitimacy of a subculture a requirement?

Beyond these questions of the interaction between culture and subculture I wonder about what creates a cultural authority that will permit the enforcement of an ethical code? Is it just a general agreement? If majority wins for the agreement, where does that leave the minority?