DesideriScuri -> RE: Another Bigot Leaves Heritage Foundation..... (5/13/2013 2:41:17 PM)
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ORIGINAL: mnottertail NO, it doesn't seem to have a hereditary link, please see your own citations: So what do the twin studies show? Well, first degree relatives tend to have "g" correlation of about 0.4 -0.5. (Perfect correlation is 1; correlation of 0 means that the 2 things in question are totally unrelated). Identical twins have a correlation of 0.85, while for non –identical twins it's about 0.6. the mid-point on the number line is the number 0.5 which falls squarely between 0 and 1. The only thing is said in this whole fuckin article is that if 1 identical twin is born smart, there is an 85% chance the other identical twin will be smart. I have accused you of innumeracy before, with resplendent cause. Read the shit you put up, and learn, like FauxNuze, that headlines that are in the form of a question usually do not conclude what they ask with any facts. You have accused me a lot of asswipe, and the most asswipe usually comes from you. quote:
Evidence for Hereditary Influences Earlier we mentioned that measures of information processing speed correlate with IQ scores. Speed of processing depends on neurological efficiency and maturation, which are genetically controlled. From this standpoint, then, we have some support for a hereditary basis for intelligence (Perkins, 1995). The fact that children with certain genetic defects (e.g., Down syndrome) have, on average, significantly lower IQ scores than their nondisabled peers (Keogh & MacMillan, 1996) provides further evidence of heredity’s influence. But perhaps the most convincing evidence comes from twin studies and adoption studies. Twin studies Numerous studies have used monozygotic (identical) twins and dizygotic (fraternal) twins to get a sense of how strongly heredity affects IQ. Because monozygotic twins begin as a single fertilized egg which then separates, they are genetically equivalent human beings. In contrast, dizygotic twins are conceived as two separate fertilized eggs. They share about 50 percent of their genetic makeup, with the other 50 percent being unique to each twin. If identical twins have more similar IQ scores than fraternal twins, we can reasonably conclude that heredity influences intelligence. Most twins are raised together by the same parent(s) and in the same home, and so they share similar environments as well as similar genes. Yet even when twins are raised separately (perhaps because they have been adopted and raised by different parents), they typically have similar IQ scores (Bouchard & McGue, 1981; N. Brody, 1992; Mackintosh, 1998; Plomin & Petrill, 1997). In a review of many twin studies, Bouchard and McGue (1981) found these average (median) correlations: Correlations of Twins’ IQs: Identical twins raised in the same home .86 Identical twins raised in different homes .72 Fraternal twins raised in the same home .60 The correlation of .72 indicates that identical twins raised in different environments tend to have very similar IQ scores. In fact, these twins are more similar to each other than are fraternal twins raised in the same home.4 Adoption studies Another way to separate the effects of heredity and environment is to compare adopted children with both their biological and adoptive parents. Adopted children tend to be similar to their biological parents in genetic makeup. Their environment, of course, more closely matches that of their adoptive parents. Researchers have found that adopted children’s IQ scores are more highly correlated with their biological parents’ IQs than with their adoptive parents’ IQs. In other words, in a group of people who place their infants up for adoption, those with the highest IQs tend to have offspring who, despite being raised by other people, also have the highest IQs. Furthermore, the IQ correlations between adopted children and their biological parents become stronger, and those between the children and their adoptive parents become weaker, as the children grow older, especially during late adolescence (Bouchard, 1997; McGue, Bouchard, Iacono, & Lykken, 1993; Plomin, Fulker, Corley, & DeFries, 1997; Plomin & Petrill, 1997). (If you find this last research result puzzling, we’ll offer an explanation shortly.) Keep in mind that twin studies and adoption studies do not completely separate the effects of heredity and environment (W. A. Collins, Maccoby, Steinberg, Hetherington, & Bornstein, 2000; Wahlsten & Gottlieb, 1997). For example, adopted children have shared a common environment for at least 9 months—the 9 months of prenatal development—with their biological mothers. Likewise, monozygotic twins who are raised in separate homes have shared a common prenatal environment and often have similar, if not identical, postnatal environments as well. Furthermore, twin studies and adoption studies do not allow researchers to examine the ways in which heredity and environment might interact in their effects on measured intelligence. Any interactive effects are often added to the “heredity” side of the scoreboard (A. Collins et al., 2000; Turkheimer, 2000). Despite such glitches, twin and adoption studies point convincingly to a genetic component in intelligence (Bouchard, 1997; N. Brody, 1992; E. Hunt, 1997; Neisser, 1998a; Petrill & Wilkerson, 2000). This is not to say that children are predestined to have an intelligence level similar to that of their biological parents. In fact, most children with high intelligence are conceived by parents of average intelligence rather than by parents with high IQ scores (Plomin & Petrill, 1997). Children’s genetic ancestry, then, is hardly a surefire predictor of what their own potential is likely to be. Environment also makes an appreciable difference, as we shall now see. Let's just take last 2 sentences and see what they say: Children’s genetic ancestry, then, is hardly a surefire predictor of what their own potential is likely to be. Genetic ancestry is not a surefire predictor. By stating that it is hardly a surefire predictor actually says it is a predictor, just not a surefire one. Which, not surprisingly, does say that genetic ancestry does play a role. Imagine that. But, let's go on to the next sentence... Environment also makes an appreciable difference, as we shall now see. The article started off with hereditary factors and then goes on to environment. So, when they state "[e]nvironment also makes an appreciable difference," the key word there is "also." So, what it's saying is that environment makes an appreciable difference, as well as the other factors discussed. And, let's see, what did they already discuss? Oh, yeah, that's right, heredity. Huh. quote:
Now, an international team of scientists have added weight to the argument that intelligence does have a genetic basis, but that it comes from multiple genes working together. ... Critics of the paper suggest that the results may not be representative of a larger area or different ethnicities due to the sample population being from one particular region. In an interview with the Los Angeles Times, Professor Deary said: 'We did not have exactly the same intelligence tests for each sample, which may have resulted in the underestimation of the effects of some genes'. Critics say it might not be representative. If something might not, what else does that mean? Yep, that it might. Now, what might it or might it not? quote:
this study 'is the first to show biologically and unequivocally that human intelligence is highly polygenic and that purely genetic (SNP) information can be used to predict intelligence'. quote:
Twin Studies Identical twins have exactly the same genes, while non-identical, or fraternal twins share about half their genes, as do all siblings. Another feature of twins that makes them an ideal choice for studies is that they tend to be raised in pretty much the same environment as each other. If a particular feature is the same in identical twins, but not in fraternal twins, then chances are it's mainly genes that are controlling that feature. So what do the twin studies show? Well, first degree relatives tend to have "g" correlation of about 0.4 -0.5. (Perfect correlation is 1; correlation of 0 means that the 2 things in question are totally unrelated). Identical twins have a correlation of 0.85, while for non –identical twins it's about 0.6. So according to the twin studies it seems that genes play a very important role, but are not the only factor, since if they were, the correlation between identical twins would be 1. Adoption Studies Identical twins reared apart are almost as similar in "g" scores as those reared together. Adopted children and their adoptive parents have a "g" correlation of zero, while adopted children and their biological parents tend to have the same correlations as any parent –child pair. So although genes don't seem to be the only thing affecting intelligence, their effects do seem to be constant and apparently not overridden by environment. Disappointingly, parenting doesn't seem to have much effect. So, thrice again, my links do support the claim that intelligence has heredity as a factor. Not once has anyone brought up any link stating that heredity plays no part. Even Ron's blither blather shows that there is a correlation between heredity and intelligence. Now, on to the support that the report was bigoted?
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