[lbo-talk] The Discussion of Black IQs Considered as a DownhillAuto Race

[Miles Jackson]

Doug Henwood wrote:
> On Nov 20, 2007, at 2:40 PM, Miles Jackson wrote:
>
>   
>> I share Doug's disgust for this shit; however, one link of his  
>> "chain of
>> illogic" is in fact well supported by research: the heritability of IQ
>> performance.  Based on twin and adoption studies, the heritability  
>> ratio
>> for IQ performance is .40 to .60, meaning about half of the  
>> variation in
>> IQ scores can be attributed to genetic variation.
>>     
>
> If true - and as I recall there are plenty of problems with twin  
> studies (e.g., how early were they separated, and how different are  
> the environments they were raised in) - then the fact that you can  
> explain just 50% of the variation in IQ between creatures sharing  
> identical genetic material is really underwhelming. And of course  
> that all has little meaning for comparing populations.
>
> Doug
>
>   
Yes.  I do want to point out that there's a large chasm between the 
claim "IQ performance is determined by genetics" and the claim "IQ 
performance is in part influenced by genetics".  Formally, heritability 
implies the latter, not necessarily the former.  By training, I'm quite 
enthusiastic about sociostructural explanations for individual 
characteristics (as I've argued repeatedly on LBO).  However, I have a 
hard time arguing away all the data that support the claim that IQ 
performance is influenced in part by genetics (the claim is based on 
many types of studies, not just twin studies).

Miles