A child must be your child, step child, adopted child, foster child, brother or sister, or a descendant of one of these (for example, a grandchild or nephew).
As a broad theory, symbolic interactionism appeared in the 20-s of XX century, in the Chicago school, its founder was an American sociologist George Mead. George Herbert Mead (1863-1931) is an American sociologist and social psychologist, who is considered a true founder of symbolic interactionism.
Many leaders in the fields of family and brief therapy acknowledge Jackson as the principle founder of Interactional Theory and Conjoint Family Therapy. Interactional Theory places emphasis on what is transpiring in the present between people as the primary data relevant to understanding human behavior.