Are Kiss and Kith related? You can do one with the other, especially grandparents...
Kiss: (verb) to touch with the lips especially as a mark of affection or greeting
Origin: Middle English, from Old English cyssan; akin to Old High German kussen to kiss
First Known Use: before 12th century
Kissing Cousin:a person and especially a relative whom one knows well enough to kiss more or less formally upon meeting. First Known Use:1941
Kith: familiar friends, neighbors, or relatives Middle English, from Old English cȳthth; akin to cūth know. First Known Use: before 12th century
Kith and Kin acquaintances and relatives.Origin: 1350-1400; Middle English
So are they related? Sadly, no. Nice theory, though.