Using a small sample of monozygotic and same-sex dizygotic twins, estimates of the heritability of certain parameters of sexual development were obtained. In the majority of instances significant values of h2 were found, suggesting that genetic factors play an important role in psychosexual development. The significance of these results is discussed in the light of current pro-environmental attitudes.
A critical examination is undertaken of the major arguments which have been advanced in support of the hyp that the 15-point X IQ gap between black & white Amer's is largely determined by genetic factors, & the conclusion is reached that they are all specious & valid. The a priori argument, which suggests that it is highly likely that such genetic diff's between the 2 pop's do exist, is shown to be illogical on 2 counts & based on an empirically unsubstantiated premise; furthermore, a more persuvsive a priori hyp in the opposite direction is formulated & defended. Attention is called to the much-neglected direct evidence, based on comparisons of the IQ scores of black people with known %'s of white ancestry, & it is shown that this evidence does not confirm the genetic hyp. The argument from compensatory educ is examined, & it is pointed out that the evidence is irrelevant even if it is reliable. The heritability argument, which is based on the findings of twin studies, is challenged by the evidence on intrauterine effects on later intellectual development, which make possible a plausible non-genetic interpretation of the findings of twin studies, & by the logical point that the heritability of a character within a pop does not bear on the origin of diff's between pop's. 2 versions of the "culture fairness" argument are criticized on the grounds that they ignore the most signif environmental influences of performance in IQ tests among the various minority groups in the US, & also pay no attention to the phenomenon of "passing for white." Finally, the ideological character of the geneticist doctrine is examined, with particular reference to the writings of A. R. Jensen (see SA 0312/B4540) & H. J. Eysenck (RACE INTELLIGENCE AND EDUCATION, London, England: Temple Smith, 1971). AA.
Data are presented on the verbal and performance (non-verbal) IQs of a sample of university scientists, their surviving fathers and male sibs.Although mean IQs differ between scientific disciplines the disciplines do not differentially attract scientists from particular socio-economic classes.The verbal IQs of both the scientists and their fathers are positively correlated with socio-economic class but only in the fathers' sample is the performance IQ/class correlation significant. The variance of both verbal and performance IQs increases from Class I to Class IIIM. The overall estimate of heritability for the verbal IQ is higher than that for the performance IQ.Verbal and performance IQs are related to the distance the scientists have moved on the socio-economic scale. The effects of social mobility on the genetic and environmental components of the verbal and performance IQ phenotypic variances are discussed.
