about 21 % of the full sibs were affected , ( 5 ) a higher number of offspring produced by dull persons and a lower number of offspring from retarded persons compared to two normal persons ( 6 ) a proportionately large number of affected children produced from matings involving one or two dull persons , ( 7 ) a tendency for dull to have additional dull children and mentally retarded parents to have further retarded children while normal parents with more than one affected child usually had further retarded children , ( 8 ) an incidence of affected parents of about 32 % , and ( 9 ) an overall empiric recurrence risk of 14 % .
C0027361
persons
C0008059
children