Since our data on low LGBT fertility is recent, you could just declare, “In earlier times, there was such strong familial pressure to marry and have kids that LGBT fertility probably used to be about average. In the absence of negative selection pressure, the true LGBT share of the population covertly rose for centuries. Then, over the course of just two generations, familial pressure evaporated. LGBTs didn’t just come out of the closet; they started having the low fertility consistent with their uncloseted preferences. Which means, ironically, that LGBT genes are now suddenly starting to disappear at the rate that one would naively expect. Yes, it’s a big anomaly; but in evolutionary time, this anomaly will be short-lived.” … Natalists often push various kinds of baby bonuses. Contrary to what you’ve heard, such incentives work well relative to the counterfactual. But what the LGBT explosion teaches us is that high doses of sheer enthusiastic social approval are strong enough to move mountains. Yes, money matters. But a full-blown fertility cult culture — complete with Parent Pride Parades — plausibly could work as well or better.