On Nov 21, 2007, at 9:17 PM, Miles Jackson wrote:
> One typical comparison is between fraternal twins (50% genetic sim)
> and
> identical twins (100% genetic sim). In each case, we're talking about
> same age sibs growing up in the same family environment at the same
> time. IQ performance tends to be more similar for the identical twins.
Again, that tells us that genetic makeup has an influence on IQ test performance. It doesn't tell us anything about heritability.
> In the adoption studies, there is a significant correlation in IQ
> performance between biological parents and children they have put
> up for
> adoption and never interacted with.
Significant? If identical twins have an r2 of .50, then what do non- twin sibs have? Parents and children? .20? That's getting down into so-what territory, even for first-degree relatives.
Doug