Intelligence is in good part heritable.

Judge as of 2018-03-22 against the behavioral-genetics literature. 'In good part' means a substantial share of the variation in measured intelligence, roughly 30% or more. TRUE: consensus reviews and meta-analyses (twin, adoption and family studies) estimate the heritability of intelligence/IQ at a substantial level (e.g. around 0.4–0.8 in adults). MOSTLY TRUE: estimates are substantial but vary considerably by age, population or socioeconomic status, which the claim leaves out. MIXED: the literature is split, with credible estimates ranging from small to substantial and no clear consensus. MOSTLY FALSE: most estimates show only modest heritability (e.g. around 10–25%), or the claim rests on estimates the field widely regards as inflated. FALSE: the evidence shows that intelligence has negligible heritability.

Set before the research began.

1. E1 Socioeconomic Status (SES) and Children's Intelligence (IQ): In a UK-Representative Sample SES Moderates the Environmental, Not Genetic, Effect on IQ PLoS ONE (Hanscombe, Trzaskowski, Haworth, Davis, Dale, Plomin) · 1 February 2012

   “Doubling the differences between the MZ and DZ correlations provides a rough estimate of the heritability of IQ. These estimates show the expected pattern of increasing heritability with age, from 30% at age 2 to 46% at age 14.”

2. E2 Socioeconomic Status (SES) and Children's Intelligence (IQ): In a UK-Representative Sample SES Moderates the Environmental, Not Genetic, Effect on IQ PLoS ONE (Hanscombe, Trzaskowski, Haworth, Davis, Dale, Plomin) · 1 February 2012

   “Although SES was measured as a continuous variable, the magnitude of genetic moderation found suggested an increase in the heritability of IQ from 5% in low-SES families (−2 standard deviations, SD), to 50% in high-SES families (+2 SD).”

3. E3 SCIENCE Science (Bouchard & McGue; American Association for the Advancement of Science) · 29 May 1981

   “For the dizygotic twins reared together, the weighted average of 32 correlations based on group tests is .60”

4. E4 Meta-analysis of the heritability of human traits based on fifty years of twin studies - Nature Genetics Nature Genetics (Polderman et al.) · 18 May 2015

   “Estimates of heritability cluster strongly within functional domains, and across all traits the reported heritability is 49%.”

E1, a UK-representative twin study, estimates the heritability of IQ at 30% at age 2, rising to 46% at age 14. Both figures meet the claim's threshold of a substantial share. E2 reports a finding suggesting IQ heritability rising from 5% in low-SES families to 50% in high-SES families, though the paper's title states that in its UK sample SES moderated the environmental, not the genetic, effect on IQ. The evidence therefore supports substantial heritability but shows it varies with age and possibly with SES, which the claim leaves out. E4's 49% figure covers all human traits rather than intelligence specifically, and E3 gives only a twin correlation, so neither is used here.