While Jack does have a pretty traditional family (no divorce here), things aren't perfect in the Gantos household. Dad is pretty much a kid in larger-sized clothing, and Mom is a bit arbitrary and unfair. Does Jack's family lean a bit toward the slightly dysfunctional side? Yes. Do they seem to love and care for each other anyway? Of course they do. Should Jack's family be perfect? Um, no. For one, that would make them boring. Perfection would also ruin one of the major points here. In Dead End in Norvelt, the family isn't necessarily the primary source of learning and development. In fact, Jack learns most of his crucial lessons from Miss Volker, and not his mom and dad.
Jack's Mom asserts that the family works as a team, but we never really see the family showing much cooperation at all.
Establishing your role within your family is a significant part of growing up.