> They're religious and conservative and hard to notice because they're too busy raising children to be visible on social media and in high culture. But

The thing is that they are quite visible, and quite a fair share of the people that are now in the group choosing to reproduce at or below replacement rates, either strategically or just by deprioritized reproduction cookies to career, etc, so that it is delayed come from those backgrounds. Biological decent doesn't dictate personal choice.