Simplex × normal is the fifth type of mating considered. The matings where one parent was tainted and the other supposedly normal, are classified here. From a study of their ancestors these normal parents appeared to be simplex, and the classification of the offspring showed more than 25% nulliplex, which is the expectation from simplex × simplex mating.
The sixth type is normal × normal, and the matings where both parents were reported normal is studied under this heading. Here, as before, a study of the ancestors of these normal parents indicates that they are simplex, and not normal. The classification of the children showed a close fitting to the expectation from a simplex × simplex mating.
A special study of the matings where one or both of the parents was migrainous or alcoholic, shows a close relationship between these conditions and epilepsy.
The following conclusions are drawn from the study.
The common types of epileptics lack some element necessary for complete mental development. This is also true of the feeble-minded.
Two epileptic parents produce only defectives. When both parents are either epileptic or feeble-minded their offspring are also mentally defective.
Epilepsy tends in successive generations to form a larger part of the population.
The normal parents of epileptics are not normal but simplex, and have descended from tainted ancestors.
Alcohol may be a cause of defect in that more children of alcoholic parents are defective than where alcoholism is not a factor.