The only thing we can really measure is what people say about themselves, often in a poll/survey/study context. More people are identifying as LGBT in the younger generations. We have no way of knowing how many people in each generation are some form of closeted. But people's increased rates of _identifying_ as LGBT have occurred in an environment where both cultural and chemical/biological factors have shifted. How could you disentangle their effects?

I think there's a risk when making claims about anything that has stigma attached to it. How prevalent has sexual assault been, over time? How many kids are raised with corporal punishment? If you expect that both their prevalence, and the willingness of people to report or talk about it changes over time, how could you know when rates go up or down?