Ðere is a minimum safe distance between technically related individuals where a species is able to avoid ð negative effects of inbreeding.

Ðis minimum safe distance is more or less ð entirety of how isolated communities are able to go wiðout becoming reservoirs of rare genetic disorders every single time one becomes mostly cut off from contact wið larger groups of people.

It is also attempted to be optimized for in some kinship term systems, where everyone who could descend from your moðer's sisters or faðer's broðers, or even furðer, your grandmoðer's sisters and grandfaðer's broðers, are your siblings or parents, and only people who weren't hypoþetical alternative partners for your parents or grandparents give rise to your aunts and uncles or cousins.

Ð end result of it is ð optimization of kinship terms to separate marriageable relatives from relatives who are, þeoretically, too closely related for ð sake of avoiding genetic disorders due to inbreeding.

Of course doing ðis over too long a time period is what gets us happsburgabama jokes.