>>13452770flynn effect gains are mostly in non-heritable, less-g-loaded subtests . basically kids growing up in the west today get far more practice in tests that are similar to IQ tests than 80 years ago and so are able to maximise the gains they can make by practicing, but those gains aren't improving the heritable part that strongly corresponds with G.
in reality the IQ of developed western societies has been decreasing since the late industrial revolution since the darwinian conditions selecting for intelligence, i.e. the conditions that meant intelligent people would have more kids reach adulthood, have been removed. Since the late 1800s or maybe as early as 1850 then it has been just as easy for the less intelligent, working class people to have children as the more intelligent middle and upper class people to have children, and the working class people have had much more children than upper class people since then causing the average genetic IQ of developed nations to drop.
