Farzandnameh (letter to children) is one of the most frequent and universal instances in the didactic literature which has focused on how parents teach children ethical rules and advise them. Although it is a kind of recurring subspecies of the genre, it has not been academically addressed in typological discussions in literary research in Persian and perhaps in world literature. In this search, parent-child interaction in the letter-writings was analyzed quantitatively and descriptively, examining the most frequent cases including the in-text features (the title, author’ s motivation, dedication, chaptering, and text history) and the out-of-text features (emotional introduction, special attention towards boys, being worried about not applying advice, emphasis on applying advice, parents' experiences, being selfish and pride in the ancestors, expressing the writer's childhood memories, simplicity and conciseness). The results of this study show that the authors of letter to children, in general, aim to teach topics such as medicine, music, alien sciences, literary sciences, religion, ideological arguments, and practical wisdom (a program to refine personal morality, family, and politics or the true form of life), so they had written their books or treatises for their children (whether real or imaginary). Moreover, due to the high frequency of counseling topics and the special rhetorical style, letter to children can also be considered as a lived genre in the form of counseling writings that has a specific structure and content and is appropriate to the culture and requirements of the time and audience expectations. What is important in distinguishing a letter to children from other counseling letters is that the creator of the work clearly states that he is writing the letter or book for the children and that there are signs of the child being and preset’ s advisement.