Sounds like an answer from a non-parent, honestly. There's a lot more to it than that, and virtually every couple I know with children thought about it a lot before going ahead.

The number one reason is because they see other families and the love and joy that their children bring into their lives. This is inspiring, and brings people around to making the decision, even if they know the sacrifices they will have to make.

Boiling it all down to pure biology is stripping parents of agency to fit your worldview.

Weird how I dont have this drive huh