There's nothing "magical" about it: Tolerance breeds openness, which in turn breeds more tolerance. There's nothing innate about prejudices against homosexuality; they are learned. If the previous generation doesn't teach them, there's no particular reason to believe that the next will come up with them on their own.

(Thanks for the press release, but I do wish there were access to details of the study, such as the methodology. Without those, there's no way to judge the trustworthiness of the reported data.)