Jalapeños are less spicy

From D Magazine:

The standardization of the jalapeño was rapidly accelerated by the debut, about 20 years ago, of the TAM II jalapeño line, a reliably big, shiny, fleshy pepper that can grow up to six inches long—with little to no heat. TAM II peppers have become some of the most popular in the processing business.

The driver of the change was the desire for processors to have predictable levels of spiciness.

Hat tip to Mark for sharing this.