Well, duh. That's because I don't know any. And probably neither do you.

And sure, humans are extremely diverse and adaptable, so you'll be able to find examples of any physically and logistically possible behavior. Eventually.

But statistically? We both know that I'm right. The Netherlands (the bike heaven) has the total fertility rate of around 1.5 And even within the country itself, Amsterdam (North Holland province) is at the second-to-last place from the bottom: https://en.wikipedia.org/wiki/Demographics_of_the_Netherland... And the highest fertility rates are in Flevoland and Zeeland that are about 3-4 times less dense.