“An imbecile drunkard is the father of three feeble-minded children. The daughter, seduced before the age of sixteen, gave birth to an idiot child; one son is a harmless imbecile, but the other is a moral imbecile, a sexual pervert, a thief on the streets, and a pyromaniac, firing in sheer wantonness a large mill property.
“Another shows the entire family for three generations below normal. Father, mother, mother’s sister, and father’s uncle, all imbecile. Five children feeble-minded. One girl had a proposal of marriage, and one boy is married to a feeble-minded girl.
“One insane woman, whose brother and sister committed suicide, had five sons. The oldest, feeble-minded, a drunkard and hobo, had one son, a criminal. The second son, insane, had three imbecile children. The third, an insane epileptic, had three imbecile sons, one of whom was an epileptic. The fourth son was insane. The fifth, apparently normal, had a morally imbecile son and an epileptic daughter.”
Yet striking as is the inheritance of these maladies, Doctor Barr points out that of the 10,000 known cases of feeble-mindedness in Pennsylvania, only 3,500 are sequestrated. This leaves a balance in that state of 6,500 totally irresponsible individuals to work havoc in society by producing their kind.
Inheritance Not a Factor in Some Cases of Mental Deficiency.—On the other hand as our data show, there remain about one-third of the mentally deficient type to be accounted for on other than a basis of heredity. As already noted, some of these are doubtless the product of suppressions of normal development by various extraneous factors operating before or shortly after birth. There is one class particularly, estimated by some authorities as constituting as high as thirty per cent. of the feeble-minded which is unusually puzzling. These are the so-called mongolians. The name is given because the features of such individuals bear more or less resemblance to those of some of the Mongolian races. The defect does not seem to be hereditary although it is usually congenital. It appears to be due to something which interferes with prenatal development. Whatever the conditions, whether lack of nutrition in the mother, alcoholic or other poisoning, the cases seem to be as hopelessly incurable as are the hereditary forms. From the social standpoint, of course, such individuals are in their immediate generation, as incompetent or as dangerous to society as those suffering from the more surely known hereditary forms of mental defect.
Epileptics.—Although epileptics are not classed as imbeciles ordinarily, as a matter of fact no sharp distinction can be drawn between the two classes. Doctor Wilmarth says, “Epilepsy and mental deficiency are as closely related as branches on the same tree.... Over one-half and perhaps two-thirds of all feeble-minded are subject to convulsive seizures at some period of their lives, and we are never surprised at the appearance of epilepsy in any feeble-minded person. On the other hand, so small a percentage of epileptics maintain normal mental actions as hardly to be worth consideration ... even those who retain a normal mind in the early stages of the diseases almost infallibly become imperfect later.” How slight a chance the epileptic has of ever becoming normal may be inferred from a statement made by Doctor Frank Billings in a paper read before the Illinois State Medical Society in 1909 to the effect that “ten per cent. or more can be cured by proper care.”
According to the estimates of “The Committee of Fifty” in the state of Illinois, who have been agitating for the establishment of a colony for epileptics, there are 10,000 of these unfortunates in that state. The consensus of opinion of experienced workers in various states is that there is about one epileptic to each three hundred fifty to five hundred inhabitants.
In Heredity Conditions of Feeble-Mindedness Are Probably Recessive to Normal Condition.—As to the mode of inheritance of the various forms of feeble-mindedness, the evidence points to such defects in the main as being recessive. However, no particular grade can be picked out and shown to be a pure recessive. For instance, the children of two epileptics will be defective but it is impossible to predict always whether the defect will appear as epilepsy or feeble-mindedness. This is doubtless due to the fact that mental deficiencies even of the inheritable type are not all due to the same specific cause, and in many cases the individual is defective in more than one direction. If one or more of a great number of units which are necessary for complete mental development are lacking, obviously mental deficiency will result. In other words, feeble-mindedness and allied disorders may not be definite characters, but simply evidences of the fact that the nervous system has not developed all factors necessary for normal mental coordination. Goddard, however, one of our best authorities on the heredity of feeble-mindedness, is inclined to regard the condition as a unit character, “due either to the presence of something which acts as an inhibitor, or due to the absence of some stimulus which sends the normal brain on to further development.”
Supposing nervous defects finding expression in feeble-mindedness, epilepsy and related conditions, to act as a Mendelian recessive, then the marriage of one such defective with another should yield only mentally enfeebled offspring. How nearly this expectation may be realized is seen from the following examples.
In an extensive study[9] of feeble-mindedness, just from the press, Doctor Henry H. Goddard points out that of 482 children with both parents feeble-minded all but six were feeble-minded. Even the exceptions may be apparent rather than real as there is possibility of mistake in judging the condition of the parents or of the children themselves. Moreover, with the feeble-minded one is not always sure of the paternity of a child, as is instanced by Doctor Goddard in a case quoted from Doctor Emerick in which of twelve children in a white family with both father and mother feeble-minded ten were feeble-minded and two were not, but these two were mulatto children.