| Show II Intelligence tellig c of Twi Twins s Compared by j I Science Physical Traits Studied T The Th most fascinating phases i 10 of twin comparisons ris ns are to the majority major major- ity ty of ot us those having to do with intellectual traits traits- writes D. D Cecal Rife in the Scientific American The ThOr relative importance of heredity and ad environment n in i- i mental up make-up haS has both been f for r centuries es and still is is a a topic sure to a lively discussion discus discus- sion in m. m sf groups of civilized man man- kind Have win studies ies shed she any y on this question Considerable r b e research has been do done dane c in Iii this tills field acid by numer numerous us' us investigators in- in n I There are are certain ain difficulties dim dim- s however ho which are arc not oft often n encountered in the study of physical traits We cannot be sure whether a a given mental test measures only innate learning capacity or whether part of the responses are arc the result of education and training Then Then too the person tested may mayor or may not respond to the best of his ability There are arc certain tests such as the Simon Simon-Binet and its revisions revisions which have been thoroughly studied by psychologists over a period of J years and nd h have ve been shown to be fairly valid measures of general l i learning arning r i g capacity aI ity L H Hundreds of twi twins s re reared red together r 1 h have v been given n gere general A tests by y various arious inv investigators st The I average pair intra difference obtained ob ob- ob- ob tai tOi d t for r 1 Identical twins vins is approximately five live points points' in iri IQ I.Q. an insignificant n figure On the theother other hand fraternal twins show on an average intro intra pair differences of from ten to twelve points which Is 11 a significant cant difference The obvious conclusion sl sion n from sucH results fa nJ that intelligence in In- t. t is to so some degree at le leat leOM t 1 dependent upon genetic m ke |
