The claim of "agricultural societies have larger families" is a cope. Smaller families is characteristic of capitalist societies but not true of non-capitalist ones. The Soviet Union had above replacement levels of fertility and this quickly decreased to Western levels after the fall of the Soviet Union. In addition, farming families mostly do not have higher fertility in the West.

Even in poor countries that have not entered capitalist economics yet, they have high birth rates even in countries with a high percentage of urban population but the moment they move West, acquire capitalism and Westernize their fertility collapses.

As Marx wrote, culture is downstream of economic conditions. Economic conditions create very particular social conditions for women that is highly dysgenic. Which is why I said, you don't pay women to have kids - that's just misunderstanding the problem.

The answer lies in what women respond to on average - which is why I said, they must be manipulated on a societal level to have more babies.