Despite a century of research on complex traits in humans, the relative importance and specific nature of the influences of genes and environment on human traits remain controversial. We report a meta-analysis of twin correlations and reported variance components for 17,804 traits from 2,748 publications including 14,558,903 partly dependent twin pairs, virtually all published twin studies of complex traits. Estimates of heritability cluster strongly within functional domains, and across all traits the reported heritability is 49%. For a majority (69%) of traits, the observed twin correlations are consistent with a simple and parsimonious model where twin resemblance is solely due to additive genetic variation. The data are inconsistent with substantial influences from shared environment or non-additive genetic variation. This study provides the most comprehensive analysis of the causes of individual differences in human traits thus far and will guide future gene-mapping efforts. All the results can be visualized using the MaTCH webtool.
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- Supplementary Figure 1: Authorship co-occurrence matrix on 2,748 twin studies published between 1958 and 2012. (368 KB)
Each colored cell represents two authors who appeared on the same paper; darker cells indicate authors that co-published more frequently. The filter of at least 25 papers per author was set for readability. The web application MaTCH has an interactive version of this matrix.
- Supplementary Figure 2: Funnel plots across all traits for twin correlations and variance components. (380 KB)
Z, Z-converted correlation; MZ, monozygotic twins; DZ, dizygotic twins; DZSS, DZ same-sex twins; MZM, MZ male twins; MZF, MZ female twins; DZM, DZ male twins; DZF, DZ female twins; DOS, DZ opposite-sex twins; h2, heritability; c2, shared environment; h2 same sex; c2 same sex; h2 males; c2 males; h2 female; c2 females.
- Supplementary Figure 3: Funnel plots for rMZ across the major trait domains. (375 KB)
The plots denote the relationship between the Z-transformed rMZ and its standard error. SE, standard error.
- Supplementary Figure 4: Funnel plots for rDZ across the major trait domains. (366 KB)
The plots denote the relationship between the Z-transformed rDZ and its standard error. SE, standard error.
- Supplementary Figure 5: Funnel plots for h2 across the major trait domains. (346 KB)
The plots denote the relationship between the Z-transformed h2 and its standard error. SE, standard error.
- Supplementary Figure 6: Funnel plots for c2 across the major trait domains. (343 KB)
The plots denote the relationship between the Z-transformed c2 and its standard error. SE, standard error.
- Supplementary Figure 7: Distribution of twin correlations and variance components in full and best models across all traits from 2,748 studies. (379 KB)
rMZ, monozygotic twin correlation; rDZ, dizygotic twin correlation; rDZSS, DZ same-sex twin correlation; rMZM, MZ male twin correlation; rMZF, MZ female twin correlation; rDZM, DZ male twin correlation; rDZF, DZ female twin correlation; rDOS, DZ opposite-sex twin correlation; h2, heritability; c2, shared environment; h2 same sex;c2 same sex; h2 males; c2 males; h2 females; c2 females. “BEST” denotes estimates from the most parsimonious models per study. All other estimates are from “FULL” models.
- Supplementary Figure 8: Distribution of differences between MZ and DZ correlations. (209 KB)
rMZ, monozygotic twin correlation; rDZ, dizygotic twin correlation; rDZSS, DZ same-sex twin correlation; rMZM, MZ male twin correlation; rMZF, MZ female twin correlation; rDZM, DZ male twin correlation; rDZF, DZ female twin correlation; rDOS, DZ opposite-sex twin correlation.
- Supplementary Figure 11: Scatterplots of all MZ versus DZ correlations. (517 KB)
Contour lines indicate the density of the data in that region. The lines are ‘heat’ colored from blue to red, indicating increasing data density.
- Supplementary Figure 12: QQ plots of the χ2 test statistics for testing the null hypothesis that 2(rMZ – rDZ) = 0 and 2rDZ – rMZ = 0 and relationship with sample size. (222 KB)
(a) The deviation from the null hypotheses is quantified with the inflation λ in the QQ plots. (b) Effects as a function of sample size.
- Supplementary Text and Figures (4,901 KB)
Supplementary Figures 1–12, Supplementary Note and Supplementary Tables 1–19, 22–24 and 26–31.
- Supplementary Tables 20, 21, 25, 32 and 33. (624 KB)
Supplementary Tables 20, 21, 25, 32 and 33.