Sui generis
In sociology, the "sui generis" is what has been externalized, then internalized in the overall public and becomes a part of society that simply exists in its construct. It is not something that is not thought to have been created, because it is imbedded in everyone's way of thinking and being. Instances include the idea of love, or going to school, or clothing belonging to a specific gender. These examples are "sui generis" for they simply exist in society and are widely accepted without thoughts of where they come from or how they were created.
Miss Peregrine's Home for Peculiar Children
Otherwise known as "syndrigast" (a word meaning "peculiar spirit" in the Old Peculiar language, which is in turn the author's adaptation of Old English, or Anglo-Saxon language), peculiar folk are a branch of humanity possessing a second soul which manifests itself in strange ways such as abnormal characteristics and abilities commonly referred to as "peculiarities". Very rarely are peculiar children born to peculiar parents as the essence or gene of peculiarity often skips entire generations, making peculiar population vastly less than that of normal people.