Studies by the late English psychologist Cyril Burt of IQ scores of separated twins strongly suggested that intelligence was inherited. A summary of recent research costs doubt upon the validity of Burt's work. (SL)

Data are presented from families of monozygotic twin pairs which give evidence of genetic variance on the Block Design Test, a nonverbal measure of intelligence. Analyses of genetic and environmental effects on behavior are possible with this kind of information. (SA)

The question as to whether males and females have different kinds of intellectual abilities is addressed. The evidence that there are some differences in cognition and perception between men and women is reviewed. (KR)