Comment by A_D_E_P_T
2 years ago
The IQs of adopted children have next to nothing to do with their environments, and much more to do with the IQs of their birth parents. IQ in general is very strongly heritable. There are several adoption and twin studies that have demonstrated this effect, e.g.: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8513766/
Trauma (physical and emotional) causing reduction in IQ is totally compatible with IQ being in part heritable.
Regarding race/ethnicity correlations from the paper you posted:
"(McGue et al., 2007; Miller et al., 2012). McGue et al. (2007) reported minimal ethnicity effects in the SIBS sample at intake, which we largely replicate in the current follow-up assessment. While rearing family socioeconomic status and polygenic scores were both moderately higher among Asian offspring (Cohen’s = d .36–.46; p < .01 ), no measure of cognitive ability differed significantly between offspring of different ethnicities. See SI Table S6 for these and other comparisons, along with a discussion of their relevance."
Also, the children in that study have not been victims of trauma (or the study has not considered and controlled for it), so it says nothing about that factor in eventual IQ of the individuals studied.
It's also compatible with low IQ causing poverty and bad parenting.
Low IQ doesn't "cause" poverty. Poverty is highly multivariate, and likely dominated by factors having nothing to do with IQ, like structural inequities in health/education access and historical lack of access to asset ownership, and exclusion from access to other vehicles of economic advancement.
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