the irish iq has always been relatively high (98)
"Another line of evidence is that the blacks have a smaller standard deviation for IQ than whites (Jensen 1973, 212)."
Don't think so. Your own table from our study above shows slightly larger Black SD.
There were too many comments on your twitter thread to read. A number of people pointed this out and I agree. The IQ gap between black and white Americans is likely entirely genetic. There are no starving people in the US nor do we have lead paint or any widespread pollutants.
It's like sex differences. The more egalitarian a society becomes, the more of the differences we see are genetic. Women can be anything in the US or Western Europe. Yet so few of them go into computer science or engineering. Instead a poor country like Romania has a lot of women engineers.
But the IQ gap between Sub Saharan Africans in Africa and whites probably has a sizable environmental explanation. Giving the Raven's test to children after they spend a day mining cobalt is not exact good data right? There's still a lot of pollution in their drinking water also.