... but my wife's folks don't. (Para. 11)
Meaning: ... but my wife's relatives don't.
folk: n. one's relatives
You can refer to your close family, especially your mother and father, as your folks. 你可以把你的家人，尤其是父母，说成是你的亲属。
a. of or having to do with the common people, their beliefs, stories, customs, and the like 民间的，民俗的
folk culture 民俗文化
folk music 民间音乐
folk dance 民间舞蹈
folk art 民间艺术