A Mexican airline’s January 2019 promotional campaign left observers (and some of our readers) wondering about the validity of an unusual discount it seemingly offered.

The advertisement, produced by Ogilvy, touted what it called a “DNA discount” incentive for travelers flying into the country via Aeroméxico. In a series of interviews, the airline sought to entice residents of the Texas town of Wharton, around 300 miles from the U.S.-Mexico border, to visit Mexico through the use of genealogy testing — the greater the percentage of “Mexican DNA” each resident had, the ad boasted, the greater the discount they would receive on a flight to…