3 ms·
IQ studies comparing genes and environment have deeper problems than failed studies. 1) genes and intelligence correlate strongest trough health. Good immune s
by nabla9 4y ago
IQ studies comparing genes and environment have deeper problems than failed studies.
1) genes and intelligence correlate strongest trough health. Good immune system => higher IQ on average.
2) the environment and the intelligence correlate mainly trough health. Prenatal and natal nutrition, and parasite load explain most of the regional IQ differences (heavy metals and pollution is also contributor).
3) the environment changes gene expression. Identical twin study where twins are separated in birth does not reliably separate genes and the environment without additional controls.
- rbanffy 4y agoIndeed. We need vastly larger samples, more geographically spread, to properly answer the question.
- nabla9 4y agoYou can't fix the problems I mentioned with more samples or geographical spread. If you want to separate IQ from health, or how genes and environment interact you need to select better controls and more specific variables. Large studies over large areas show is that intelligence differences are dominated by parasite load and nutrition.
- rbanffy 4y agoYou still need a very large sample to control for those. You may find some correlation with genetics when you analyse subsamples with identical parasite load and nutrition.