Why is it mentioned only concerning Milcah that she was Haran’s daughter? Was Sarai any less of a daughter to him that no mention is made of her father, Haran? The Bais Yitzchak explains that there are various ways for one to establish his reputation in a community. First and foremost is to earn and establish one’s notability in his own right, either through scholarship, virtuous deeds, impeccable character, etc. One only has to mention the name of certain individuals and their stature and good name precedes them.
There are those who are recognized only based upon their yichus, ancestral lineage, their father or grandfather etc. was prominent. Yet others, have neither their own established reputation nor notable lineage. These individuals are invariably “identified” through their children. They have a child whose reputation lends credit and distinction to his parents.
Sarai was a righteous woman, a prophetess whose exemplary virtue was manifest and acknowledged by all. She needed no “familial” background to serve as introduction. Her sister, Milcah, on the other hand, was not well-known. It was, therefore, imperative to mention her father’s name. There was a problem, however: Who was Haran? He had as yet not established himself as a noted personage. Consequently, the Torah introduces him as the father of Milcah and Yiscah, who really was Sara Imeinu. His yichus, lineage, was derived from his daughter’s reputation. How important it is to establish oneself as a person in one’s own right, rather than rely upon an unearned reputation based merely upon pedigree.