Many historical constructions about matriarchy and patriarchy, about the family structure of the tribal period in Europe needed philological (etymological) study for authenticity. This is practically the first time O. N. Trubachev does this in the proposed book. A group of Slavic terms for blood and inherent (by marriage) kinship helps to reveal the social secrets of that distant time. Their comparative historical research is carried out on the basis of other languages of the Indo-European family. The book is intended for historians, philologists studying Slavic antiquities, as well as for graduate students and undergraduates studying thematic groups of words in the course of historical lexicology and the history of literary languages.~ ~ ~ ~ ~For To display some characters of this text (such as yat and yus, as well as letters of the Slavic and Baltic alphabets), it is recommended to use unicode fonts: Arial, Times New Roman, Tahoma (but not Verdana), Consolas.