There is no doubt that family relations are of influence on Iranian Penal Law. But there are certain questions: “are the way in which and the extent to which these relations influence penal rules based on an informed, reasonable approach which is, in turn, founded on scientific principles and in accord to the practical requirements or are they far from a penal-legislative policy and only a translation of juridical sources and foreign laws without an understanding of and taking into account the influence of this point [penal-legislative policy]?” To reply these questions, the author has studies the penal-legislative policy when influenced by family relation from three respects: The extent to which and the way in which family relations influence testimonies of relatives, jurisdiction, execution of religious punishment (hadd) by father and husband, that father is not punished for [crimes he committed toward] his offspring, in terms of correspondence between legal and juridical approaches; Legal corrections stemmed from family relations in elimination of paternal guarantee in quasi intentional murder in punishing those who commit incest, not taking into account relativeness as a cause to stop prosecution or exempt someone of punishment, change in the structure of paternal relatives [of a murderer], competence of the judicial authority, limitation of the scope of murder in penal cooperation, in terms of a purposeful, sustainable, and wellfounded legal approach toward family relations. The way in which family relations influence cases such as financial interactions, nakedness [in presence of each other], and absence in legal deadlines in terms of similarity between basis and the scope of impact exerted by relativeness on penal laws.