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Show s es a. 53 Not Necessarily Lacking in Mental or Physical Vigor Neer Absolutely Identical in Looks or Actions Often. No More . Alike Than Brothers and Sisters Born Many Years Apart X, SSX r MStf-- j - 'm' V. fy 'Cl MV SI A&J' V JU C -- wasd A H f t ;-- . $ J f . . W V WJH 7- -: A J J x :i .j ;A JjJ$ Wv A. ' I , X ' - . . X:-i- ' ' ,i C c i ' - f . n ' A 4 : vs 4 ylff V Ac a V f'V A 4 i V- f sWWPi V X A1 - l I V . ! T1 . X T , r These Twin Sisters Are Very Much Alike, but Science Finds That a Great Many Brothers and Sisters Born Years Apart Would Show Just as Close a Resemblance If They Could Be Viewed Side by Side at the Same Ages. has recently made some very and Important discoveries about twins, and as a result of these we now know that a great mqny Ideas on this subject which have long been accepted as true are entirely Incorrect. Tains are not necessarily lacking 'In mental or physical vigor; they .are never absolutely identical in the way they look or act, they often differ from one another as widely, as brothers and sisters bora many years apart; the body of a twin is likely to be more symmetrical than that of one not a twin these are just a few of the things which are pretty well established by the recent scientific Investigation. This investigation was begun over a sear ago by the American Genetic Association, an organization devoted to study of the laws of heredity and their application to the improvement of plants, animals and human racial stocks. Appeals were sent to all parts of the world for detailed information concerning twins, together with photographs of them at various ages. Responses were received from more than 600 pairs of twins and their parents, and with them came 160 pboto-- v graphs of twins. With this mass of life histories and pictures at ttaefr disposal the scientists connected with the association have been able to make a more exhaustive study of the whole subject of twins than has ever before been attempted. From time immemorial many parrats have felt serious regrets over tbe arrival of twins owing to the popular belief that such children were less vigorous than others not likely to be long lived and not so well equipped for success in life. It was long supposed that there was strong scientific basis for this belief, particularly in the case of what are known as identical twins. , These are children sprung from a single parent cell instead of being the product of two unions of two different mother and father cells as what are called fraternal twins are. Many scientists thought it quite reasonable to suppose that a baby having only half a cell from which to draw its heredity would be less vigorous than one springing from a whole cell. B at- - the recent investigation by the genetic experts leaves no ground for believing any such thing. On the contrary it presents a great deal of evidence which seems to show that It is a highly fortunate thing for a child to be born a twin. Tbe record of the Grosvenor twins Gilbert and Edwin Grosvenor would of Itself be almost sufficient to shatter tbe theory that identical twins are naturally III fitted for success In life. As students at Amherst College these twin brothers divided highest honors In the class room snd on tbe tennis court.' After graduation one, cs builder and dfiector of the National Gee piHC Society, and the other as as-- 1 attornev-genera! a and partner in , counrv'i greatest law firms, otv tr abilities aa he iu.jnsfrated X P, SCIENCE 1 iti tbeir whole lives the two have .ailed more than a pound in weight, i Be. "V Prints of the Left Solee of Twin Brothers, Showing Great Similarity in the General Plan of the Lines But Many Differences in the Minor Details. Similar Differences Prevail Throughout the Mental and Physical Make-U- p ef Twins and Prevent Their Being Absolutely Identical, In college their grades never varied-morh than of one per cent. Their tailor says that ,one of the twins has a short left arm and the other a short right arm. Although absolutely dependent upon glasses, each can wear the others. Their illnesses have often coincided. They have always been devoted friends, and frequently their letters cross. Most of their tastes are similar, but there is one striking exception they have never agreed when it came to girls! They look enough alike to be twins, is an expression one often hears, but it is a statement which has no good dcientiflo basis. As a matter of fact, while certain twins show profound resemblances in both mental and physical traits, others show no such unusual similarity. Twins that look and act alike attract our attention more than the dissimilar ones and this is what has given rise to the idea that all twins are very much like one another. Of the 600 pairs of twins studied by the Genetic Association a large America number showed a remarkable degree of resemblance, but on the other hand many showed the most surprising dissimilarity. And it is believed that the average of all the twins in the world is considerably lower even than it was found to be In this somewhat selected group. Exact correspondence In tbe height of twins is not at all nnusual, and a difference of a quarter of an inch more or les3 one-tent- Is common.- - Yet variations of several inches sometimes occur, and considerable difference are sometimes found between twins otherwise very similar. Complete identity in weight, or a difference of only a pound or two. Is common. The changes In weight of many twln3, as in the case of the Grosvenor brothers, are always, parallel, so that they never differ from each other by more than a small amount. Perfect uniformity in color of hair and eyes is the rule with twins. But, on the other hapd, twins one of whom has dark eyes and the other light are rather frequent, In general, similarity with reference to one trait la correlated with reference to most other traits. Rarely are there only a few points in common. In other words, either twins look very much alike or else thev show a wide difference in appearance. The same general laws hold good for gait, tone of voice, reaction to foods and lX If J Vn dfL, An American Mother and Her Two Pair of Twin Who Were Among Those Weighed Measured and Carefully Studied by the Scientists in Making the Discoveries Explained on This Page. flelal, but pervade their whole being. A few dissections of Identical twins which have been made reveal remarkable similarity In the configuration of the train and In tbe structure of the muscles and blood vessels. The tendency of such twins is always to absolute Identity, but they never quite attain It The explanation of tbe fact that twins are never actually identical la probably to be found in the same causes which produce variations between the two sides of the body tn a single individual. But Professor H. H. Wilder holds that while tbs variation between two twins may be as great or greater than It is between the two sides of an ordinary individuals body, it ia tar less in tbe body of each twin. In other words the body of a twin generally allows greater symmetry ' than that of the ordinary individual. Fraternal twins those derived frpm two unions The Palm Prints of Twins Showing, as in the Case of the Soles, a Similarity in General of two different mother Pattern, but a Great Difference in the Way the Details Are Worked Out. and father cells are never so much alike as susceptibility to disease, as well .as for the hemispheres of their brains differently, those of the identical variety. In fact their mental capacities, intellectual tastes and and thus Influence the amount of use that resemblance to each other is only, about likes and dislikes One pair of twins state is made of the left hand In one infant and equal to the average for all children of that bananas make both very sick. Two the in the other. right same family. Brothers and slaters the little acrobat? who are familiar figures in Do twins like one another better than bora many years apart would doubtless the motion pictures always got hungry anybody else? Yes, says science, as a look as much alike aa fraternal twins, if it and sleepy at exactly the same time. general rale they do. But it is noticeable were possible to see them together at the Over and over again the two twins of a that this fondness is usually strongest besame ages. Of course, the resemblance pair are found to have virtually the same tween twins who are not only of the same between fraternal twins tends to Increase preferences and aversions in their studies. sex, but otherwise very similar. if they grow up together, owing to their One twin and her sister commonly dream t Right here It should be mentioned that being subjected to the same environmental about the same persons at the same time, statistics based on thousands of cases show influences. even when sleeping In wylely separated that about one pair of twins In every three But the most interesting question in places. And not only that they actually born consists of a boy and a girl. Yet of connection with the study of twins ia dream the same things about these per160 pairs of twins whose pictures were Bub-- 1 whether a degree of difference similar to sons! . mitted to the genetic experts only 22 wer that which keeps twins from being absoRather a surprising number of the huncf both sexes. This small percentage is lutely Identical and often tuakes them dreds of pairs of twins studied were comaccounted for by the fact that of dif- quite unlike in mental and physical traits posed of one right and one left handed ferent sexes twine are rarely can also manifest itself in tbeir moral pigeon Individual. It has been suggested that as fond of ODe another as those of the natures. Is it for one twin to become tbe perhaps on twin Is frequently the "mirror eame sex and, therefore, often drift apart worst ofpossible criminals while he other becomes Image of the other1, left handed and with in life. early honest, useful member of society? Can Are twins ever so much alike that "even an heart and other organs reversed In their we have Js-- e single pair of twins indiA Is now further investigation fheir own mother cant tell them apart"? viduals as different in symmetry. .character aa Dr. under way to determine if this is true. No. says science, the resemblance between Some who believe that right or left similar pairs of Individuals la never quite Jekyll and Mr. Hyde? Sciences latest discoveries lead to the handedness is an acquired characteristic" complete, and practically every pair la belief that the moral natures of twins may and not hereditary havs still another exfound to differ more or less widely In at least one respect Although marked slml-- . show aa great if not greater differences planation to offer. Twin babies generally face each other in lurlty is, with rare exception, the rule, than their physical and mental traits. We have seen how even the way twins lie their beds, and if care is mot taken to absolute identity is not attained. each othef In their crib may make Science believes that the resemblances change them about frequently tbeir heads A become a asymmetrical on opposite sides found in Identical twins twins derived tbeir bodily mechanisms different. This, It is suggested, may possibly affect from a single parent cell are not super- - study of the palm and foot prints of various Crot Bn tain Bitbt tC) 19'JO Intemiuon.l Fnture Serric. lac. d e tw-ln- s i fao-Jnrf- c; I twins shows that while the lines tend to be closely similar In their general pattern there are always numerous minor points of difference. Similar small points of difference In the development of the brain cells might easily result in mor&i natures that would be as different aa right ia from wrong. Environment also plays an Important part in making the moral as well as the mental and physical natures of t ms alike or unlike. Twins living together under precisely similar conditions naturally tend to become more and more alike, bat wide differences In them would probably result if they were separated and forced to live under conditions not at all the same. Take rfJhe case of two middle-agetwins whose life , histories were among thc--e la height, , studied by the genetic experts, weight, tastes, dispositions and talent these men are the same. They have lived and worked together continuously fer twenty-fivyears, and haye never beea separated. Nine persons out of ten cannot tell them apart. How far could different environments have forced these men apart in character! Supposing that one had grown up in China, speaking only Chinese, and the other in Spain, speaking only Spanish, would they still look as much alike as they do, and when we cam to know them would they keem as much alike? Is it not possible that if one had, been subjected fop years to evil influences and the other only to good they would have become quite different in character? These questions are most interesting, and it is hoped that further study of twins will enable science to answer them, The importance of twins in furnishing icience with evidence of the limitations of snvironment cannot be exaggerated. Identical twins are the only human beings in die world who have exactly the same heredity. If e can find out the characteristic ways in which they remain the same throughout life, the qualities and habits and mannerisms which persist unchanged in them both, in spite of their living in entirely different surroundings, we shall know much moie than we do at present about what attributes are hereditary and fixed and what are those which we can hope to modify by environment and education. Any exact knowledge we can gain by a were study of two Identical twins separated from each other as babies and brought up in different towns under entirely different circumstances, scarcely knowing each other, will give us a clearer idea that) we appear to have now of wbat changes tn our bodies, and, perhaps, too, tn some of our mental and moral charao-- . era, are clearly due to the thing we eat. ,he exercise we take, the associations we nake, and the work We do to our environment,, as It is call and what changes, or failures to change, can be correctly .raced to the very beginnings of our Uvea, i i |