Abstract
This article addresses the prohibition of marriage between in-laws in the direct line. It focuses on affinity as a legal family relationship that arises between a stepchild and a stepfather (stepmother) when the stepfather (stepmother) marries the stepchild’s biological parent. The considerations in this article aim to demonstrate the fundamental thesis: that the prohibition of such marriages between persons related by affinity in the direct line should be lifted due to the lack of rational grounds for its maintenance.