Chimerism is what happens when cells from one twin are present in the other. For example, white blood cells with Y chromosomes would be found in the female twin. Vigier et. al, 1989.
Piaget's theory of cognitive development. Piaget's theory of cognitive development is a comprehensive theory about the nature and development of human intelligence. It was first created by the Swiss developmental psychologist Jean Piaget (1896â1980).
The theory is considered  constructivist  , meaning that , unlike nativist theories ( which describe cognitive development as the unfolding of innate knowledge and abilities ) or empiricist theories ( which describe cognitive development as the gradual acquisition of knowledge through experience ) , it asserts that we construct our cognitive ...