kith and kin

Reader's Digest 2月号に掲載の記事からです。
Favourite advice I plan to go pass on to kith and kin (once I figure out what kith means)
When I was a self-conscious teen, my mother told me, "You think people are thinking about your zit or your large nose, but they're not. No-one else is thinking of you as much as you think they are, because just think how much you're not thinking of other people."
And she was trying to cheer me up.
"kith" は知らない単語なので辞書を引きます。
・Collins Dictionary: one's friends and acquaintances (esp in the phrase kith and kin): We will not tolerate any tardiness because it is our loved ones, our kith and kin, who are suffering.
・Merriam-Webster's Learner's Dictionary: old-fashioned : friends and relatives: They invited all their kith and kin to their new home.
・Dictionary.com: acquaintances, friends, neighbors, or the like; persons living in the same general locality and forming a more or less cohesive group.
古い言葉で今では "kith and kin" と言う表現でしかほとんど使われないようです。