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).
Erikson's Stage Theory of Personality Development. Asserts that people evolve through eight stages over the life span and each is marked by a psychosocial crisis by confronting a fundamental question. Development is enhanced when a crisis is solved with a healthier alternative.