At least in my area the real reason for larger families in social housing or even rented/owned housing is because peoples first “child bearing relationship” breaks up (often due to stresses/money worries from having children, even when planned, they are expensive) and you thus very often get biological kids and stepchildren sharing the same family house. often the age ranges are quite wide so grandchildren also end up in this same family house.
I can understand why this happens as if I got with a woman who already had a kid I’d end up producing one of my own simply not to feel cuckolded – which I know isn’t right at all but I am not going to lie about my own male instincts.
Also my own parents planned me for 1975/6 but “Dad got overexcited and forgot his precautions” in winter 1971, and that put a lot of financial strain on my parents, and more so when my sister was born in 1980 in similar times of austerity. And both of them had full time jobs. children in most nations regularly shared rooms until the 1980s, but even in ancient times were usually separated when puberty arrived in order to prevent the risk of incest (even in Norfolk).
I don’t think young women in some areas breed simply for financial benefits but in all female mammals motherhood usually brings a rise in happiness and self esteem (or the species would go extinct). you can see this in the animal rescue homes (or large family households with pets) where cross-species adoption is not uncommon – in the village I work in two cats take it in turn to stand guard over the local children playing…
it would make far more sense to create less stressful societies so couples first child bearing relationships survive and then people feel the need to have less children to start with.
