When I think of a big family, I think of a well-oiled machine of wholesomeness. The father is confident and wears respectable slippers around the house. The mother is serene and spins wool from the goats in the backyard into beautiful cloth from which she creates all the family's garments. The homeschooled children have clean, smiling faces (never a strand strays from the girls' braided hair); they all help each other and, when feeling mischievous, giggle together quietly in Sanskrit with great and charming humility. After the older children's double reed ensemble practice, they pose for a photographs on a sunny lawn, then skip off holding hands to churn the week's butter. Obviously this will never be us, which is why I'm usually scowling.
This is not the vision liberals have of big families. I read a book a while back called The Pecking Order. The basic idea was, all parents hate at least one of their kids, so try to keep your reproduction to a minimum so as not to create unnecessary black sheep who will drag society down. One family profiled to illustrate this truth was particularly interesting to me: a nice Lutheran girl married an Orthodox doctor and converted; next thing you know she's alienated from her staunchly occidental community and babies keep crawling out of her body (for a total of seven or eight, I think). The neglected and disconnected children grow into unproductive adult lives of confused listlessness. In other depictions of big families I've come across in liberal writing, maladjusted and uncontrollable kids and feces-smeared walls seem to be obligatory story elements. Vicodin-hoarding mommas with gray skin hide in closets during the brief intervals between the popping out of one urchin and the next (and they're always "popping out"). There are usually lots of molting animals in the house, too, just in case the chimpish children weren't generating enough feces for the walls to be sufficiently smeared.