“And finally, I’m not going to go into a debate about IQ, since obviously a URM has a lower IQ since they are more likely to be socioeconomically disadvantaged, less likely to graduate from highschool, more likely to be incarcerated and less likely to have good healthcare. When you look at all of these factors they are likely to have a negative effect on IQ since IQ is highly variable during adolescence when the environment becomes the major factor.”
I’m going to need some proof on this.
IQ can be affected by the environment during adolescence, but its effects go away as you approach adulthood. In other words, no matter how much you try to make yourself smarter, you will always fall back to the IQ determined by your genetics.
Now, I have my doubts about IQ being molded by the environment during adolescence. I feel that the easier IQ tests given to children may have influenced results.
Traits become progressively more genetically controlled from birth through age four, as well as later.
Source: P. Vernon (editor), Biological Approaches to the Study of Human Intelligence, 1993, pp. 123-6
At birth identical twins correlate with each other in height and weight by only .62 and .63. But when they are eight years, most identical twins correlate .99.
Similarly, when mental ability of infants is measured by the Bayley Scale of Infant Development, at three months the correlation between identical twins is .66, at six months the correlation is .75, at eighteen months .82.
Source: Pages pp. 215-16 of R. S. Wilson, “Twin Growth: Initial Deficit, Recovery, and Trends in Concordance from
Birth to Nine Years”, Annals of Human Biology 6, 1979, pp. 205-20; page 304 of R. S. Wilson, “The Louisville
Twin Study: Developmental Synchronies in Behavior”, Child Development 54, 1983, pp. 298-316
The 60% genetics argument for IQ is from politically correct academics who averaged out the .4 correlation for small children with the .8 correlation for adults.
In the Rising Curve, pages 16-17, Neisser observed, “It is now widely agreed that h^2 [heritability] for IQ lies between .4 [for smallchildren] and .8 [for adults] in the U.S. White population. … When biologically unrelated children are raised in the same home (as in many casesof adoption), the correlation between their IQ scores is unimpressive in childhood and near zero as they grow up!”
The 20% that is not genetic is determined prenatally, by the intrinsic variability in developmental processes, especially in the formation of the nervous system in the early stages of its development in the mother’s uterus.
Source:C. E. Finch and T. B. L. Kirkwood, Chance, Development and Aging, 2000, Oxford University Press, New
York; P. C. M. Molenaar, D. I. Boomsmsa, C. V. Dolan, “A Third Source of Developmental Differences”,
Behavior Genetics 23, 1993, pp. 519-24
IQ is not influenced at all by the environment.