4 ms·
Debunking the Minnesota study of twins reared apart (2022)
- rbanffy 4y agoI'm not sure DZA pairs being correlated disproves much - they share about 50% of their genes, so some correlation would be expected if you assume intelligence is inherited. The other omission, of whether the twins are actually raised apart, is much more significant. The study would have to account for that, by introducing an apartedness score. Another possible interesting pool would be fertility clinics, if we can track donors with their offspring, whatever correlation we find is 100% nature and absolutely zero percent nurture.
- nabla9 4y agoIQ 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.