Reviews data from the "High School and Beyond" study to examine sibling intellectual symmetry and the degree to which family background affects the siblings' intellectual ability. Finds considerable symmetry in intellectual skills. Discovers little impact on symmetry from gender or birth order. (CFR)

Maintains that intellectual ability has become a more important determinant of occupational success in recent decades, resulting in increased social class differences. Finds that, contrary to the usual view, class differences have become smaller and current social problems cannot be ascribed to low-ability people in the lower classes. (CFR)