As an illustration, using the steatosis example, consider the impact of rosiglitazone, an antidiabetic drug that is a full agonist of peroxisome proliferator‐activated receptor γ (PPAR‐γ), which can activate steatosis (Lehmann et al. 1995), and perfluorooctanoic acid (PFOA), a highly stable chemical with widespread human exposure and uptake (Fry and Power 2017), which is a partial agonist of PPAR‐γ and a full agonist of PPAR‐α, which inhibits steatosis by increasing the β‐oxidation of fatty acids (Vanden Heuvel et al. 2006). The gene discussed is PPARG; the disease is steatosis.