MZ twins reared apart correlate at 0.76 IQ. MZ twins reared together correlate at 0.86 IQ. IQ heritability is 50-70% overall. Heritability rises to 85% in late adulthood. Shared environment falls to 0% by young adulthood. Unrelated adoptees reared together have random IQ similarity in adulthood. Wilson Effect shows homes explain nothing about adult IQ differences. High IQ genes drive people into enriching environments. Same genes affect IQ from childhood to adulthood. SES and education are highly heritable. Early interventions boost IQ temporarily but gains vanish by adulthood. National military and school studies confirm heritability despite full population range. Adoptive homes are better but do not inflate heritability estimates. Twin pre-adoption contact does not affect IQ similarity. Parents treat MZ and DZ twins equally. Misperceived zygosity shows treatment similarity irrelevant to IQ. MZ twins with separate placentas match monochorionic IQ similarity. GCTA gives lower-bound heritability confirming twin studies. GCTA heritability rises with age like twins. Dozens of IQ genes identified in large samples. Heritability data strengthens genetic explanation for group IQ differences.