Intelligence, family size and birth order: Some data from Kuwait

The relation between intelligence and family size and birth-order was examined in a sample of 4643, 8–15 years old in Kuwait. There was a correlation of –.05 between intelligence tested with the Standard Progressive Matrices and family size, much smaller than those typically found in a number of studies in the United States and Europe and effectively negligible. There was a slight tendency for first and second born children to have higher IQs than later born but again the effect was negligible. This association was present for children aged 8–10 and for those aged 12–16 years. It is considered that the results are incompatible with the theories of Zajonc and Blake that family size and birth-order have significant effects on IQ, and support the conclusion of Rodgers that family size and birth-order have no significant effects on IQ.