Only child syndrome refers to the theory that children who do not have siblings are more likely to grow into maladjusted adults. The theory is believed to have its roots in the work of Granville Stanley Hall, a psychologist who presented his only child syndrome theory in 1896. Hall believed that only children are more likely to have problems forming relationships and functioning socially and that they may even intentionally distance themselves from others out of a sense of superiority. Hall believed only children are more likely to be eccentric, unpopular, selfish loners who may not achieve as well as children who grew up with siblings. Other experts believe, however, that only children are at no disadvantage socially, and, while they may form closer relationships with their parents, this often translates to higher levels of success in life, rather than higher levels of maladjustment.
Some psychologists and historians point out that society has long stigmatized parents of only children, out of a belief that the refusal to give a child siblings could be harmful to the child. Some studies seem to suggest that many parents decide to have a second child largely out of concern for the first child's well-being. Historically, the only-child stigma may have been inextricably linked to the realities of life in an agrarian culture, where large families were more likely to prosper and more likely to produce children who lived to adulthood. Some experts believe that Hall's theory of the only child syndrome grows from the cultural realities of his time, and others point out that his research methods may have been flawed.
Research conducted throughout the 20th century, and continuing into the 21st century, suggests that the only child syndrome may be a myth. Only children are often believed more likely to grow into spoiled, selfish adults who have problems forming friendships and close relationships. Many point out that only children are often in a more privileged position than children with siblings, since they can receive a larger portion of their parents' time, attention, and resources. For these reasons, some experts claim only children may, in fact, grow into more accomplished, capable, reliable adults with higher self-esteem. Some adult only children may, however, have problems forming close relationships, and may maintain stronger ties with their parents than do children who have siblings.
There is some evidence to suggest that only children may have some problems interacting socially during their early school years. Some studies suggest, however, that, by the time only children reach their teen years, they are generally on a social par with their peers who have siblings. As they mature further, they may be more likely to pursue higher education, and may be generally higher achieving than peers who have siblings.