And I read a famous novel about such twins, Le grand cahier (The notebook, Das grosse Heft) by Ágota Kristóf. They did speak to outsiders, but made up their ow

And I read a famous novel about such twins, Le grand cahier (The notebook, Das grosse Heft) by Ágota Kristóf. They did speak to outsiders, but made up their own logical and esp. moral rules how to treat them, and they write down their findings, when they can eliminate all personal interpretations and feelings. Everything must be objectively true, to them and their limited view.