I'm looking for specific, real cases in which a causal relationship was inappropriately inferred from evidence of a correlation.
Specifically, I'm interested in examples that meet the following criteria:
- Existence of the causal relationship was accepted as fact widely enough to have notable effects (on public policy, discourse, individual decisions, etc.).
- The link was inferred solely on the basis of correlative evidence (perhaps along with the existence of a coherent but unproven causal mechanism).
- Causality has been objectively falsified or at least called into serious doubt.
The two examples that came to mind for me aren't quite ideal:
- Sodium intake and blood pressure: As I understand it, it has since been determined that salt intake only increases blood pressure in sodium-sensitive individuals. The existence of a valid causal relationship (although not quite the one that was originally accepted) make this example less compelling.
- Vaccines and autism: I may have the background wrong, but I believe this link was surmised on the basis of both correlations and (fraudulent) experimental evidence. This example is weakened by the fact that (fake) direct evidence existed.
Note: I've seen this similar question:
My question differs primarily in that it focuses on notable, real-world examples and not on examples in which a causal link is clearly absent (e.g., weight and musical skill).