Going native

Associated with colonialism.

The term going native indicates the colonisers' fear of contamination by absorption into native life and customs.

The construction of native cultures as either primitive or degenerate in a binary discourse of "superior coloniser and inferior colonised" led to a widespread fear of "going native" in colonised states in the early 20th century. The suggestion is that the associations with other races can lead to lapses from European behaviour and moral and physical degeneracy, or even madness.

Examples
In Katherine Mansfield's The Woman at the Store, the woman of the title has been living apart from other Europeans for so long that she has degenerated physically (she used to be beautiful, now she is described as unpleasant to look at). The outdoors have encroached into her home; language associated with animals and madness is repeatedly used to describe her and her daughter's actions and words.  Her isolation from civilisation has led to ultimate moral degeneracy: the killing of her husband.