heritability of IQ increases with age (up until age 20, at least)
Straight forward result of how the brain learns. Cortical/cerebellar modules start out empty and mature inwards out—starting with the lowest sensory/motor levels closest to the world and proceeding up the hierarchy ending with the highest/deepest modules like prefrontal and associative cortex. Maturation is physically irreversible as it involves pruning most long-range connections and myelinating&strengthening the select few survivors. Your intelligence potential is constrained prenatally by genes influencing synaptic density/connectivity/efficiency in these higher regions, but those higher regions aren’t (mostly) finishing training until ~20 years age.
Straight forward result of how the brain learns. Cortical/cerebellar modules start out empty and mature inwards out—starting with the lowest sensory/motor levels closest to the world and proceeding up the hierarchy ending with the highest/deepest modules like prefrontal and associative cortex. Maturation is physically irreversible as it involves pruning most long-range connections and myelinating&strengthening the select few survivors. Your intelligence potential is constrained prenatally by genes influencing synaptic density/connectivity/efficiency in these higher regions, but those higher regions aren’t (mostly) finishing training until ~20 years age.