Yap et al. (2021, Cell) measured how much trait variance the microbiome explains — using b², the microbiome analog of heritability. The answer depends entirely on which trait you ask about.
In September 2025, the White House announced that Tylenol during pregnancy causes autism and ordered warning labels on the drug. But the very study they cited — Ahlqvist et al. (2024, JAMA) — concluded the opposite. Here's what happens when you partition the variance.
Both studies extend Fisher's VP = A + D + E + Environment to real-world biomedical questions — partitioning variance across different layers to identify what genuinely contributes to trait variation.