Shard environment effects are important in determining BMI in childhood but disappear in adolescence.
A meta-analysis found 88 BMI twin studies found a random effects meta-estimate for heritability of 0.75. However, we should adjust by two factors:
-0.06 because heritability is falling over time (see Table 2)
+0.03 to account for the studies which used self-reported zygosity and self-reported BMI (see Table 3)
This results in a meta-estimate of around 0.72.
However, BMI generally correlates r~0.28 between husbands and wives, which suggests the true heritability is around 0.80.
However, weight fluctuates over time as well. I looked at the control group's data from the CALERIE-2 trial and found the correlation between clinically measured weight on a particular day and the median clinically measured weight over 2 years was only ~0.92 calerie.
If we model
The heritability on a given day as a function of long-term heritability plus noise
Genes affecting long-term heritability
Then, the implied heritability for 2-year BMI is around 0.95. Presumably, it would be even higher if we used a longer time-frame.
tl;dr: Almost all variance in long-term BMI is due to variance in genes.
Oreffice, S., & Quintana-Domeque, C. (2010). Anthropometry and socioeconomics among couples: Evidence in the United States. Economics & Human Biology, 8(3), 373-384. https://doi.org/10.1016/j.ehb.2010.05.001
Elks, C. E., Den Hoed, M., Zhao, J. H., Sharp, S. J., Wareham, N. J., Loos, R. J., & Ong, K. K. (2012). Variability in the heritability of body mass index: a systematic review and meta-regression. Frontiers in endocrinology, 3, 29. https://doi.org/10.3389/fendo.2012.00029
calerie. Duke University of Medicine. https://calerie.duke.edu/
Chiappori, P. A., Oreffice, S., & Quintana-Domeque, C. (2012). Fatter attraction: anthropometric and socioeconomic matching on the marriage market. Journal of Political Economy, 120(4), 659-695. https://doi.org/10.1086/667941
Dupuy, A., & Galichon, A. (2014). Personality traits and the marriage market. Journal of Political Economy, 122(6), 1271-1319. https://doi.org/10.1086/677191
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