The Effects of Family Size, Birth Order, Sibling Separation and Crowding on the Academic Achievement

Family constellation variables such as family size, birth order, spacing of children, and crowding were related to academic achievement when IQ was controlled. The sample consisted of 306 girls and 247 boys from large and small families living in four suburban Boston communities. It was found after controlling for IQ that small family boys tended to have better grades than did large family boys. First born girls had higher academic achievement than did latter born girls. Thus a sex-specific pattern of relationships between family constellation and academic achievement appeared. It was suggested that first born girls were more likely to develop patterns of responsibility and hard work which helped them academically. Boys in small families were possibly more oriented toward adult values while large family boys may have been more influenced by peer group, anti-academic values. Crowding was negatively related to achievement for both sexes but its effect became non-significant when IQ was controlled. Sibling spacing was significantly related to achievement only for boys and also lost significance when IQ was controlled