CHAPTER IV. Consanguineous and Neurotic Intermarriage

CONSANGUINEOUS AND NEUROTIC INTERMARRIAGE

Byron has sung of the old popular belief in the advantages of cross-breeding, which arose originally in the practice of exogamy (marriage outside the tribe), or, more often, outside those having the same totem, or coat-of-arms. In all probability casual observation of deformities after intermarriage enforced the prohibition which arose after the killing of female children had led to exogamy. Totemic relationship was often far from being consanguineous. The idea of incest is, as Byron's stanza denotes, of religious origin rather than innate. Its criminal nature is often removed by priestly dispensation in Latin countries. From this practice sprang the medical, theologic, and legal notions to which D. H. Tuke thus refers: "The danger arising from marriages of consanguinity has been insisted upon from time to time by medical writers, and has been recognised by ecclesiastical authority, civil law, and by popular feeling. As regards ecclesiastical and civil law, it would be more correct to say that the marriage of those very nearly related has been forbidden on other grounds than that of the alleged danger to mental health. At the same time the justice of such laws receives support if medical observation leads to the conclusion that consanguineous marriages tend to generate idiocy and insanity."

The biologic evidence from the experiments of Maupas on parthenogenesis, elsewhere cited, is seemingly supported by the results of animals breeding in-and-in. The evidence advanced against such marriages seems at first sight exceedingly strong from a biologic standpoint in man.

Rilliet cites cases tending to show that consanguineous marriages, in themselves pernicious, tend with certainty to lower vital force. The effects he divides into two categories; those which relate to the parents, under which head are:--

a. Failure of conception.

b. Retardation of conception.

c. Imperfect conception.

Those which relate to the progeny:--

a. Imperfections of various kinds.

b. Monstrosities.

c. Imperfect physical and mental organisation.

d. Tendency to diseases of the nervous system, such as epilepsy, imbecility, idiocy, deaf-mutism, paralysis, and various cerebral affections.

e. Tendency to strumous diseases.

f. Tending to die young.

g. Tendency to succumb to disease which others would easily resist.

C. H. S. Davis, of Meriden, Connecticut, states that intermarriages in families lead to a degeneration that manifests itself in deaf-mutism, albinism, and idiocy. Isaac Ray is of the opinion that consanguineous marriages repeated through successive generations account for the numerous instances of insanity and idiocy occurring in quiet rural populations of New England, far from the excitements of city life, which are generally supposed to be more productive of mental unsoundness.

S. M. Bemiss, of New Orleans, Louisiana, giving a report of the condition of the offspring of 580 intermarriages of first cousins, gathered mostly by medical men from nearly every State in the Union, says: 2,778 children were born of these cousins, of whom 793 were defective, 117 deaf and dumb, 63 blind, 231 idiotic, 24 insane, 44 epileptic, 189 scrofulous, 53 deformed, and 637 died early.

While these figures seem very demonstrative, they contain a great many elements of error. One of these is incidentally pointed out by Arthur Mitchell, who finds that under favourable conditions of life the apparent ill effects of consanguineous marriages are frequently almost nil, whilst if the children are ill-fed, badly housed and clothed, the evil may become very marked. He calculates that the percentage of consanguineous marriages generally in Scotland is 1·3, or ten times less than with the parents of idiots. Taking his figures a strong case seems to be made out in support of the opinion that idiocy, among other evils, results from intermarriage. Langdon Down, although his figures are not of so unfavourable a character, admits consanguinity as one of the causes of deterioration.

George H. Darwin concluded from a careful investigation that about 4 per cent. of all marriages in England are between first cousins, and between 2 and 3 per cent. in the smaller towns and in the country; with these he compared the rate of similar marriages among the parents of lunatics and idiots in asylums, and found it to be about 3 or 4 per cent.--not higher, therefore, than in the general population.

Huth cites instances occurring regularly at the present day among certain isolated communities (St. Kilda, Pitcairn, and Iceland) without apparent evil consequences to the race. Such marriages were common among the North American Indians and the South Sea Islanders, people among whom idiocy and other degenerate hereditary conditions were remarkably rare. These cases, Strahan remarks, deal with peculiarly healthy communities. Therein lies the secret of such intermarriage proving innocent of evil to the offspring. Were such intermarriage common among the degenerates the result would be disastrous.

In 1869 the New York State Medical Society appointed a committee to investigate the influence of consanguineous marriages upon the offspring. Their results show clearly that if the family be free from degenerate taint, marriage among its members in no way diminishes the chances of healthy offspring. This conclusion is in accord with the findings of recent investigators like Anstie, George Darwin, and A. H. Huth, according to whom there is no greater amount of morbidity or abnormality among the offspring of consanguineous parents than among the children of parents not so related, provided the parents be equally free from tendency to disease or degeneration. With a perfectly healthy stock, as every breeder of animals knows, remarks Strahan, "in-and-in breeding" may be practised with impunity, but where the stock is tainted with disease or imperfection, safety is only to be found in "crossing."

Where the error lay in the old doctrine, upon which was founded the prohibition of consanguineous unions, was not, as Strahan remarks, in asserting that disease and deformity were more often met with in children of these than in those of other unions, for such is true, but attributing these unhappy results to the mere fact that the parents were related by blood. Over and above the fact that these consanguineous marriages are almost certain to transmit in an accentuated form any defect or tendency to disease already present in the family, there is no physiological reason why such marriages should not take place. Breeders of prize stock frequently breed "in and in," not only with impunity, but with marked benefit. But this fact, while going to prove that it is not the mere blood relationship of the parents which induces the degeneration so often found in the children of consanguineous marriages, can but rarely be advanced as an argument in support of the marriage of blood relations. The stock-raiser only permits the more perfect members of his flocks and herds to continue their kind, and for this reason the "in-and-in" breeding is innocuous, just as it would be in the human family under like conditions. But where shall we find the perfect human family? Such families are certainly rare. The laws of natural life have been so strained and perverted that almost every family nowadays has a taint or twist of some kind, and as all such imperfections are transmitted and rapidly deepened and fixed in the family by the intermarriage of its members, it is best that such unions should be forbidden.

Recently acquired characters, whether physiologic or pathologic, are very liable to disappear when the individual bearing such characters intermarries with another not having the same character. The natural tendency in all such cases is to revert in the offspring to the normal or healthy type, so that unless the new character be very deeply impressed upon the parental organism it is almost certain it will not appear in the offspring, if the other parents have nothing of the character. But when both parents are possessed of the character, whether it be physiologic or pathologic, this natural tendency to revert to the original is often overborne and the character is repeated in an accentuated form in the offspring.

Now this accentuation of all family characters is what must always happen in the case of consanguineous marriages. If there be any taint in the family each member of the family will have inherited more or less of it from the common ancestor. Take the case of cousins, the descendants of a common grandparent who was insane and of an insane stock. Here the cousins are certain to have inherited more or less of the insane diathesis. Even if the taint has been largely diluted in their case by the wise, or, more likely, fortunate marriages of their blood-related parents, yet will they have inherited a certain tendency to nervous disease, and if they marry they must not be surprised if that taint appears in an aggravated form in their children. Some of the children of such parents are generally idiotic, epileptic, dumb, or lymphatic, and the parents marvel whence came the imperfection. It may be in some cases that the parents, and possibly the grandparent, of the unfortunate children, have not up till that time displayed any outward evidence of the tendency to disease which they have inherited and handed on to their descendants; and, not looking farther back, the parents boldly assert that such a thing as insanity, epilepsy, scrofula, &c., is unknown to their family. They themselves have never been insane; why, then, should their children? In like manner children may be epileptic, blind, deaf-mute, lymphatic, cancerous, criminal, drunkards, or deformed from direct inheritance, and yet the family line be honestly declared to be healthy. Hence the truth of Sir William Aitken's maxim, that "a family history including less than three generations is useless and may even be misleading." From the foregoing it is evident that the similarity of temperament induced by a common environment, and which Strahan would call "social consanguinity," must be a potent factor in the production of all hereditary degenerations. Living under similar customs, habits and surroundings, labouring at the same occupation, indulging in the same dissipation, tend to engender like diseases and degenerations, irrespective of any blood relationship. Hence it not seldom happens that persons not even distantly related by blood are, in reality, much more nearly related in temperament than cousins, or even nearer blood relations who have experienced widely different modes of life. This "social consanguinity" is the great curse which dogs every exclusive tribe and class, and hurries them to extinction. It has largely aided real or family consanguinity in the production of the diseases and degenerations which have so heavily fallen upon the aristocracies and royal families of Europe.

A crucial test of the opposing positions taken respectively in such a positive manner by Bemiss and Strahan would be a family intermarrying extensively, but placed under favouring conditions unlikely of themselves to create degeneracy. Excellent cases of this kind are furnished by Bourgeois and Thiébault. Bourgeois gives the history of his own family, which was the issue of a union of the third degree of consanguinity. During the ensuing 160 years there were ninety-one marriages, of which sixteen were consanguineous. All of these latter were productive. There was not a single case of malformation, or other physical or mental disease in the offspring.

Thiébault reports the case of a slave-dealer who died in the year 1849 at Whidah, Dahomey, leaving behind him four hundred disconsolate widows, and about one hundred children. By the order of the king the whole family were interned in a particular district, where reigned the most complete promiscuity. In 1863 there were children of the third generation. Thiébault, after verifying these facts, states that at that time, although these people were born from all degrees of incestuous unions, there was not a single instance of deaf-mutism, albinism, blindness, cretinism, or other congenital malformation. From these cases it is evident that the position of Strahan is not too strongly taken.

While it is true that "like clings to like," still this does not imply kinship, but it very often implies likeness in mental characteristics. This tendency has been shown to be present in the neurotic by Roller, De Monteyel, Kiernan, Bannister, and Manning, so far as Germany, France, the United States, and Australia are concerned. Bannister puts the statistical proof of this tendency very forcibly as follows: "There are in Illinois, according to the most recent estimates, in round numbers, about 6,000 insane, or one to a little over 500 of the population. Even if we double, treble, or quadruple this frequency to include all that have been or are to be insane, as well as those insane at the present time, it would not appear that there was much probability of two insane persons being married according to any ordinary law of chances. In fact, we find four out of the 104 with insane heredity had both father and mother insane. In one of these cases the insane heredity involved both parents and both grandparents on each side, though in the case of the latter the histories show it only as collateral. Besides these, three patients had direct paternal and collateral maternal heredity; two had direct maternal and collateral paternal heredity, and in one case there was collateral heredity of insanity on both sides. This makes altogether nearly 10 per cent. of those with insane heredity with it on both sides, maternal and paternal, and thus favoured with a double opportunity to inherit mental disease. If we add to this the instances where, with insanity of one parent, there is reported either epilepsy, hysteria, or drunkenness, 'brain disease,' nervousness, &c., of the other, the ratio of double inheritance rises to over 20 per cent."

The beneficial effects which may result from atavism are, it will be obvious, offset by this tendency of the neurotic to intermarry, thus perverting the principle of atavism to the assistance of degeneracy.

The age of the parent plays a part in degeneracy. Conger (whose results have been corroborated by Joseph Workman, of Toronto, and Kiernan, of Chicago) points out that in all degenerative forms we must take into consideration this factor, since it determines the development of degeneracy in childhood. Hereditary taint may be transmitted to descendants as a simple neuropathy, as a neurosis, or as a defect of development reaching even to idiocy. Conger finds the prevailing age, especially the age of the mothers of degenerates, is often between twenty and twenty-five years, and that hence there exists a relation between this age and the greater transmission of degeneracy to the offspring. Marro, who has specially investigated the influence of the age of the parents, both in the normal population and among criminals, finds that among all classes of criminals there is an excess of immature parents (under 26) or senile parents (over 40), and that only petty offenders possessed a normal number of mature parents (26 to 40 years). A man between 20 and 25 is in as favourable condition for procreating degenerates as the very aged. Because of incompleted organic development he has been unable to free himself from hereditary taint which he transmits to his descendants, but which in maturer age, through the influence of adaptation, evolution, or education, might perhaps be more or less notably modified.

The organism between 20 and 25 is yet incomplete; education has not been able to exert much influence in determining those possible changes which are adapted to modify congenital tendencies. In a word, the individual between 20 and 25 feels too much the influence of atavic characters, and too readily transmits to his posterity the brands of degeneracy. Experience has made it well known that the children of the aged readily show degenerate types. Many children of old fathers have undoubtedly inherited all the characters of the weakness of the age in which they were begotten. Old age represents the period of retrogression, of involution, and hence readily transmits the mark of degeneracy. The children of either too young or too old parents, failing to escape hereditary predisposition, may from birth inherit those characters which are proper to incomplete organic development or to the period of involution.

Kiernan has had under observation a Nova Scotian family of Scotch extraction, the mother of which continued to bear children until she was 63 years old. There had been no pregnancy between 50 and 56. At 56 a son was born who had ear, jaw and skull stigmata, and became a periodical lunatic at 25. A son, born a year after, was a six-fingered idiot, with retinitis pigmentosa. (These last expressions of degeneracy are, as Darier has shown, often associated. Darier's cases had the following hereditary antecedents: One father had hemeralopia; one mother had defective vision; a grandfather was blind at 30; a grandfather was blind in one eye, and an uncle had congenital iris coloboma. Only one patient examined did not have hemeralopic descendants. Six patients examined belonged to five different families, all consisting of five or six children, one-third of whom had hemeralopia. Among thirty-five children there were eleven hemeralopes and two six-fingered children, who died too young to determine the existence of retinitis pigmentosa. The disease in all began in childhood, and hemeralopia was absent in but one case.) Three of the next children (two boys and a girl) became paralytic idiots in infancy. Here the degeneracy was expressed in that tendency to miliary aneurismal weakness of arteries to which E. C. Spitzka, called attention over a decade ago. One of the next children was a periodically sexual invert female. The last child was an epileptic. The children born before the age of fifty were normal and averaged 60 years of age.

Matthews Duncan, Arthur Mitchell, and Langdon Down, have called attention to the influence of premature and late marriage in the production of idiocy. Factors capable of producing idiocy are of course capable of producing less decided expressions of degeneracy.