The heritability of intelligence is one of the most replicated findings in psychology — and one of the most consistently misunderstood. Six decades of twin and adoption studies, recently joined by genome-wide association studies on samples in the millions, converge on the conclusion that genetic differences explain a substantial fraction …
A 2007 paper in Journal of Medical Genetics reported something unusual: an extended British family in which a single genetic mutation caused both cone-rod dystrophy (a form of progressive blindness) and substantially elevated verbal cognitive abilities. The eight affected family members had verbal IQs averaging 127.3 — nearly two standard …
The heritability of intelligence sits at roughly 70–80% in adulthood, but genome-wide association studies aggregating thousands of common variants currently account for only about 10–15% of variance in cognitive ability. The gap — the so-called “missing heritability” — is one of the most discussed problems in modern intelligence research. Epigenetics …
