Abstract
A group of 161 children from incestuous matings has been examined and compared with 95 of their half-sibs. The parental age distribution showed considerable differences between the groups, and the period of observation was longer in children of incestuous origin The educational level of the parents was below average; 20 of the 141 mothers were mentally retarded. Information about the fathers was less complete in both groups, but 8 of 138 fathers in the consanguineous group were known to be mentally subnormal. Prenatal, neonatal and infant mortality was higher among children from incestuous unions, and mental retardation as well as congenital malformations, single and multiple, were far more frequent among these children than among their half-sibs who were offspring of unrelated parents.