Family size, birth order and IQ components: a survey of a Cambridge suburb

Abstract

SummaryThis study examines the relationship between family size, birth order and IQ components. No significant associations were found in either non-manual or manual social groups between IQ scores and family size. The correlation coefficient between verbal IQ and family size in the non-manual group was positive and differed significantly from the negative manual group value. Birth order effects were noted; the association differed significantly between non-manual IQ components and between social groups.