[rapind]

I'm not married to either reason, but I'm just feeling very skeptical about your assumption.

A) I don't think we would see a massive number of older people coming out of the closet, because this culture change is generational. Most of your peers aren't going to change their minds just because a younger generation is more tolerant. It's the same reason my 100 year old (really!) grandmother may still use the occasional racial slur. I definitely think there's more peer friction for an older LBGT individual than a younger one.

B) I don't think these numbers are actually out of line with the impact of cultural change.

C) Base on your linked datas, religion may also be a factor. Given that religion is on the decline in the US, especially among millennials, I wouldn't rule that out as a factor either.

It's probably a combination of factors as usual, and maybe endocrine disruptors is one of them.