The relation "is the birth parent of" on a set of people is not a transitive relation. However, in biology the need often arises to consider birth parenthood over an arbitrary number of generations: the relation "is a birth ancestor of" ''is'' a transitive relation and it is the transitive closure of the relation "is the birth parent of". | The relation "is the birth parent of" on a set of people is not a transitive relation. However, in biology the need often arises to consider birth parenthood over an arbitrary number of generations: the relation "is a birth ancestor of" ''is'' a transitive relation and it is the transitive closure of the relation "is the birth parent of". |