We been through all this stuff upthread.
You want to claim negative externalitites of fewer children on account of expensive housing? What happened to the population explosion? Fewer humans, less global warming. Positive externalitites.
There are certainly negative externalities: https://www.cnn.com/2023/03/17/asia/japan-population-crisis-countryside-cities-intl-hnk-dst/index.html
Those are pecuniary externalities, money, not physical harm. My not having children hurts you through the way Social Security is financed and it benefits my wife and me equally. Even steven. So, pay my wife and me to have children. Physical harm, so-called technological externalities, is reduced by having fewer children. We're better off on average if there are fewer children on account of the population explosion and global warming.
