Family ties, by class

Compared to their working-class and poor counterparts, the middle-class children we observed are more competitive with and hostile toward their siblings, and they have much weaker ties with extended family members.

Annette Lareau, Unequal Childhoods: Class, Race, and Family Life, 2d ed. "with an update a decade later" (Berkeley, CA: Univ. of California Press, 2011), ch. 3