Birth order: a critical review.

As the number of birth order studies continues to burgeon, it seems appropriate to review the state of this research area. This paper examines theories, findings, problems, and possibilities. Theories which incorporate the guiding assumptions of most birth order studies include intrauterine or physiological, only-child uniqueness, dethronement, anxious or relaxed parent, sibling influence, and economic. Findings are compiled under personality adjustment and problems, education-achievement-intelligence, anxiety-affiliation-dependence-conformity, and miscellaneous. The two most consistent findings in the birth order literature are: (1) greater educational attainment, including college attendance, among first-borns (including only children), and (2) first-borns are more affiliative and dependent than laterborns. Problems involve cohort and demographic difficulties, needed controls and specifications, the restrictiveness of early socialization theories, and researcher-induced bias in experimental studies. These problems themselves may also be viewed as possibilities, as they are solved, but three specific possibilities which should be pursued are studies of whole or completed families, theoretical expansions, and sophisticated statistical controls.