Twins Grace and Virginia Kennedy were severely neglected by their San Diego parents, attended minimally by a German-speaking grandmother. They saw no other children, rarely played outdoors, and did not go to school.

They were 8 years old when a speech therapist realized they had invented their own language:

GRACE: Cabengo, padem manibadu peeta.
VIRGINIA: Doan nee bada tengkmatt, Poto.

It was apparently a mix of English and German, with some original words and grammatical oddities.

Their father soon forbade their speaking it, saying, “You live in a society, you got to speak the language.” They learned English, but they still bear the emotional scars of their neglect: Virginia works on an assembly line, and Grace mops floors at a fast-food restaurant.