A famous Russian folk song, proverbs and sayings about a mother‑in‑law and son‑in‑law are the key elements of the analysis of the relations between a son‑in‑law (a younger member of the male family) and a mother‑in‑law (an older member of the female family). This analysis is also based on the etymological data and the author tries to answer the question: what is the hidden relation between the two families the members of whom are married? Many papers have been written on that matter. This article describes this relation as a gradual process of building the indirect connection between the mother‑in‑law and son‑in‑law. This is a symmetric/asymmetric relations which only seems to be mutually linked and tied. The emerged and shaped relation attitude direction – from mother‑in‑law to son‑in‑law – is presented here as the act of attracting and repelling. By means of fulfilment and satisfaction it implies the necessity of the adaption but not subordination as well as the hidden favour of the unlimited reproductive power. On the other hand i.e. the direction from the son‑in‑law to mother‑in‑law, the attitude is completely different which means the partial rivalry and repelling attraction. The daughter (from the mother‑in‑law side) and the fiancée/wife (from the son‑in‑law side) is completely out of these relations.