Note that the selection bias has existed throughout history. Every kid assumes that having children is the natural order of things, because their sample usually consists of their friends and all their friends' parents (by definition) had kids. However, when I look at my parents' friends (or even siblings), a lot of them were childless or died young. U.S. fertility rates today [1] aren't appreciably different from what they were in the late 70s and early 80s.

[1] https://www.macrotrends.net/countries/USA/united-states/fert...