I read the Marginal Revolution blog now and then. One of the links highlighted was this one. I'm not gay no have any agenda, just found this interesting.
Explaining the LGBT Explosion
"Over time, the LGBT phenotype is exploding while the LGBT genotype is imploding."
"As I explain in my book on human genetics, twin and adoption researchers have long credited some version of this “discredited” idea. While almost all studies find that genetics matters, virtually none asserts that the heritability of sexual orientation is even close to 100%. Ergo, homosexuality must, to some extent, be “acquired.” While that hardly implies that any specific mechanism - such "recruitment" or "media depictions" - works, the idea that homosexuality can be spread is the unheralded scientific consensus."
and
"What's going on? The answer is clearly not, “Gay genes exploded in the population.” Gays have far fewer biological children than straights. Fertility was conceivably equal back when almost all gays lived in the closet, but there can be little doubt that during the last fifty years, gay genes have become less prevalent."
So as media depictions skew more positive, more people decide to "try out" the lifestyle, and a certain number of those decide to stay with it. That's what I get from the article anyway.