This essay traces the formation of notions of selfness and kinship in medieval Karaite law through analysis of commentaries on the prohibitions to marry close-kin members. By examining what it takes to become a relative within kinship, either consanguineal or affinal kin-ties, the study explores different notions of selfness that stand at the base of these legal trends and approaches. It also brings forward Karaite texts that have largely been ignored in modern scholarship; some of these are medieval manuscripts presented in print here for the first time. Karaite authors discussed in the essay include Anan b. David, Ya'qub al-Qirqisani, Levi b. Yeft, Yeshuah b. Yehudah, Solomon b. David, and Yehuda Hadassi.