The town of Roseto, Pennsylvania, had very low levels of coronary artery disease. The population smoked, ate lots of fat, and mostly worked hard manual jobs. The experts went to study it, and came up with a cultural hypothesis to explain it all.
"The Roseto Effect"
I am skeptical, and I know about random clumping.
Related topic: Now They Tell Us — Fat’s Not Bad for You. A true case of "Never mind, the experts were wrong."