>>thauma+(OP)
That is similar to the many family movies today: It shows the situation of specifically those where this ideal idea of family actually works. I doubt that was common in the middle ages. It worked best for those who owned something, like craftspeople or land-owning farmers, and then for their first heir who would inherit it all.
>>nosian+if
Landowning farmers is a gigantic chunk of the population, far bigger than you seem to be imagining. (Technically, many of them "rented", but "renting" land in medieval Europe was a stronger form of ownership than "owning" it in the modern United States is.)