Genes, Meat, or Soy: What Best Predicts Human Height?

Average height at age 18 is partly inherited and is also an imperfect cumulative marker of growth conditions from prenatal life through adolescence. Maternal and early-childhood undernutrition predict later growth (Victora et al., 2008), while repeated diarrhoea contributes to stunting (Checkley et al., 2008). NCD-RisC’s 200-country trajectories show how much childhood and adolescent height varies across place and time.

Linear growth requires adequate energy and a digestible supply of indispensable amino acids. The FAO’s Digestible Indispensable Amino Acid Score, or DIAAS, evaluates protein quality amino acid by amino acid. Mathai and colleagues’ growing-pig assay found substantial digestibility differences among dairy and plant proteins; Herreman and colleagues’ review found that animal-sourced proteins often score higher on average, although variation within both categories is substantial. DIAAS rates individual foods, not whole-diet health or effects on human height.

Height is also highly polygenic. Yengo and colleagues mapped thousands of common-variant associations, allowing part of the measured genetic signal to be summarized in a polygenic score. A PGS is not a complete measure of genetic potential, and standardizing it as a Z score does not solve cross-ancestry portability or population structure. Omitting genetics can distort an ecological comparison; including a PGS does not eliminate genetic confounding.

Here, “meat” and “soy” are title shorthand. The actual exposures are national animal-protein supply—including meat, dairy, eggs, fish, and seafood—and plant-protein supply from the full food system, including grains and legumes.

This replication asks four questions:

• Across the 18 years preceding height measurement at age 18, are animal- and plant-protein supply associated differently with national height?

• Do either protein source’s returns diminish as supply rises—and, if so, where does the curve begin to flatten?

• How much predictive information does a standardized height polygenic score add on its own and alongside diet?

• Do the answers survive stricter population-size thresholds and adjustment for broader national development?

The answers do not fit neatly into a genes-versus-nutrition contest.