[galtonsieve]

The N. vs S. Korean example you mention is explicitly discussed in one of Hsu's articles. (Secular change in height due to improved environmental conditions.)

http://arxiv.org/abs/1408.3421

Section 2.3:

"Let me reiterate that within a range of favorable environments (i.e., providing good nutrition, hygiene, and access to education), evidence strongly supports the claim that individual differences in cognitive ability are largely associated with genetic differences.

Figure 8. Increase in stature in European countries over time, almost +2 SD. Nutrition, hygiene, and average number of years of schooling all improved dramatically over the last 100 years, leading to improvements in both physical and mental development."

You should probably read his paper carefully before making ad hominem attacks. Save your SJW signaling.