I've heard this kind of commentary a lot, but I still believe it's much more of a case of "people not wanting to have kids and then giving climate change as the reason" than climate change actually being the deciding factor in not having kids. I think in most cases it's more akin to virtue signaling. The modern world, especially in the US, is quite unfriendly to having kids. Both parents have lots of other opportunit…
From my experience parents are often great for their children but the trade off is they often become worse members of society, switching to focusing time and resources on their family (to give their genetic material an advantage) rather than any wider potentially more utilitarian outlets or considerations.