Attachment theory
Attachment theory describes the dynamics of long-term relationships between humans
Interpersonal relationship
An interpersonal relationship is an association between two or more people that may range from fleeting to enduring. This association may be based on limerence, love, solidarity, regular business interactions, or some other type of social commitment. Interpersonal relationships are formed in the...

. Its most important tenet is that an infant needs to develop a relationship with at least one primary caregiver
Primary caregiver
A primary caregiver is the person who takes primary responsibility for someone who cannot care fully for themselves. It may be a family member, a medical professional or another trained professional. Depending on culture there may be other members of the family engaged in care. This concept is very...

 for social and emotional development to occur normally. Attachment theory is an interdisciplinary study encompassing the fields of psychological, evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

ary, and ethological
Ethology is the scientific study of animal behavior, and a sub-topic of zoology....

 theory. Immediately after WWII, homeless and orphaned children presented many difficulties, and psychiatrist
Psychiatry is the medical specialty devoted to the study and treatment of mental disorders. These mental disorders include various affective, behavioural, cognitive and perceptual abnormalities...

 and psychoanalyst
Psychoanalysis is a psychological theory developed in the late 19th and early 20th centuries by Austrian neurologist Sigmund Freud. Psychoanalysis has expanded, been criticized and developed in different directions, mostly by some of Freud's former students, such as Alfred Adler and Carl Gustav...

 John Bowlby
John Bowlby
Edward John Mostyn "John" Bowlby was a British psychologist, psychiatrist and psychoanalyst, notable for his interest in child development and for his pioneering work in attachment theory.- Family background :...

 was asked by the UN to write a pamphlet on the matter.