EN
This study is devoted to the phenomenon of quasi-family relationships in the context of research into the household (and court society) surrounding an unmarried Polish prince. The intimate life of Prince Sigismund Jagiellonian, later Polish and Lithuanian King Sigismund I the Old, was analysed. At the centre were the circumstances of the prince’s cohabitation with Catherine Telniczerin, a burgher woman of Moravian origin, and the illegitimate children that came from this relationship. At the same time, the social conventions of the region and the time and their influence on the “public” form of a morganatic, illegitimate union was also examined.