What’s more, your IQ scores tend to vary over your lifetime—tests designed for five-year-olds show a lower degree of difference between poor people and wealthier people than tests designed for eleven-year-olds (von Stumm and Plomin, 2015). Maybe instead of thinking of that as a “failure to thrive” because of some innate predilection for stupidity, it’d be better to think about that as potential evidence of accumulated harm.
