Two of a Kind

In the year 1582 a William Shakespeare married an Anne Hathaway. Little is known of the progress of their union, but of their progeny, one fact is certain: Mrs. Shakespeare gave birth to twins. Doubtless this fact, if it did not inspire, at least aided the playwright in accurately describing the behavior of twins as he did in Twelfth Night, as he did again in The Comedy of Errors.

Whatever may have been the reasons for his writing about twins in these plays and others, it was a fortunate compulsion. Twins, are among the most engrossing of human phenomena. Twins are principal characters in The Bridge of San Luis Rey, brilliant best-selling novel by Thornton Wilder, himself one of twins. Almost every person includes in his acquaintance a pair of twins and contemplates their doings with delight and astonishment. For this reason, a wide interest attaches itself to a research begun last week by the University of California. Learned faculty members planned to assemble 500 pairs of twins and to study, with the utmost care, the details of their likenesses or their dissimilarities. A similar research has been announced by the University of Chicago.

Had such a research been made in the past, there would indeed have been many a strange brace of simultaneous children for scientists to study. Doubtless the savants of California wished that they could include, among their specimens:

Romulus and Remus, who were expelled from Alba with disgust and alarm and who must later have had their eccentricities increased by the diet of acidulous milk with which an undiscriminating wolf supplied them;

Castor and Pollux, who were the products of Jupiter's miraculously unconventional affection for Leda and who were worshipped, by credulous Greeks, on account of their coincidental birth as well as their divine paternity;

The Gordon brothers, British soldiers, who entered the army on the same day, became full generals on the same day, received the K. C. B. at about the same time, who were authorities on the customs and conditions of India, where they were stationed and where they were famed as the "Gemini Generals."

Nor would the scientists have scorned such contemporary couples as:

The Sharp twins, Summers H. and George of West Virginia, politicians also, whose mutual affection is state-known;

The Dolly Sisters and others who, sometimes dishonestly, have claimed twinship for exploitation in circus and theatre.

The most notable living family of twins in the U. S. was produced by Mrs. Andrew Koger of Council Bluffs, Iowa, and her husband, Andrew Koger, carpenter. They have four sets of twins healthy and growing, named, according to the unfortunate habit of emphasizing the abnormality of twinship by imposing artificial likenesses, Clyde, Claude, Addie, Abbie, Floyd, Lloyd, Jean and Jeannette.

Present knowledge of twins and twinship may be grouped under two heads:

Physical. In the genus homo there are three kinds of twins, Fraternal, Identical, Siamese. Fraternal twins are twins in time only. They make their entry into the world together but are completely separate individuals, the product of two fertilized eggs, having separate fetal membranes, not necessarily of the same sex, and as different biologically as any two members of the family born at different times. The young of most animals that produce litters are like fraternal twins; a fertilized egg for each animal.

Identical twins are more conspicuous members of society. They are the mirror images of each other and all the world's their stage. The product of a single egg which sometime in the course of its development has divided, they are much alike in biological construction, as they are in appearance. There is a greater similarity between the corresponding hand or foot of each twin, than between the hands or feet of either one.

The lower animals rarely indulge in this form of biological sport, with the exception of the Texas armadillo* which reproduces regularly in this way. It bears four young of the same sex, having a common set of embryonic membranes, strikingly similar in general configuration, all coming from a single egg. Thus they parallel as quadruplets the conditions of human identical twins. Exactly what causes the egg to divide is not definitely known. Dr. Horatio H. Newman, zoologist at the University of Chicago, has patiently pursued simpler species in the hope of finding a clue. After sacrificing several starfish he has shown twinning among echinoderms to be caused by retardation of development in the egg. Whether this is true of the human ovum remains to be proved. What is true is that identical twins are the closest approximation to different human beings with exactly the same heredity. They form the original rope for the tug of war between Heredity and Environment.

The third type of twins is the Siamese. These twins are the products of a single egg but, less fortunate than identical twins, they are not even separate individuals.

Psychological. Obviously twinship need have no mental effect on fraternal twins other than the general effect of being the same age and subject to similar environment.

Identical twins on the contrary are as alike mentally as physically whenever they are brought up together. Psychiatric literature is full of the case histories of identical twins stricken by the same psychoses at the same time. They have the same hallucinations, hear the same voices, suffer from the same delusions. No single instance has been found of one twin going insane while the other remained sane. Sometimes this has been shown to be the result of association, and separation in the ward has brought about changes in the character of the dementia. Would each have gone mad if the existence of the other had been unknown? There are doctors who believe they would; that having the same inheritance, developed from the same egg, the insanity is a proof of an inherited emotional instability that would have manifested itself at the same time whether the twins were together or apart. Others claim the mental disease to be the result of environment and association; insist at least that identical twins would not go simultaneously mad or have the same type of insanity if they had not been brought up together. This, in extreme form, is the field of the present investigation.

There is some doubt as to whether Siamese twins should be discussed in terms of the singular or plural, although from the examples of mental incompatibility they seem occasionally less congenial than identical twins. Margaret ("Maggie") and Mary ("Puddin' ") Gibbs of Holyoke, Mass., reputedly the only U. S. born and bred Siamese twins, vaudeville artists, deny that they are identical. "We have different ideas of pleasure," they say. In England alcoholism and prohibition are united in one pair of Siamese twins.

Dr. G. P. Crowden, physiologist of University College, London, made a 25 year study on a pair of identical twins. They had the same illnesses at the same time during this period. Their profile photographs superimposed in any year resulted in a perfect outline, with no marring double line. X-ray photographs of their skulls superimposed in every part, and their body measurements, height, weight were practically identical. Finger prints of one were mirror images of fingerprints of the other. The blood composition and count, the temperature and respiration rates were the same. They had the same temperaments and attitudes of mind. Accused of cheating in an examination because they had made the same mistake in the same problem while the rest of their papers were identical, only the statement of the form master that they were at opposite ends of a long hall and could not possibly have conferred vindicated them.

*Texas armadillo--Dasypus novemcinctus texanus.