The king selects seven descendants of Saul from two distinct family lines. The first group consists of two sons born to Saul by Rizpah, daughter of Aiah. Although Rizpah was a concubine and her children lacked full legal standing, they were still recognized as Saul's sons in every meaningful respect [ביאור שטיינזלץ].
The second group includes five sons attributed to Saul’s daughter Michal, described as having been born to Adriel. This presents a significant historical contradiction. Michal was never married to Adriel; it was actually her sister, Merab, who married him and gave birth to these five sons. Furthermore, another biblical account explicitly states that Michal remained childless until the day of her death [רלב״ג].
To resolve this discrepancy, commentators universally agree that while Merab physically gave birth to the boys, Michal was the one who raised them. Because she took on the daily role of their mother, the text attributes the children to her. This establishes a profound biblical principle: anyone who brings an orphan into their home and raises them is viewed as if they had physically given birth to them [רש״י].
This phenomenon, where the person raising a child is considered the true parent, appears in other biblical narratives. For instance, in the Book of Ruth, the community declares that a son is born to Naomi, even though Ruth was the biological mother. Similarly, the Torah introduces the generations of Aaron and Moses but proceeds to list only Aaron's biological sons. This phrasing is used because Moses raised and taught his nephews, elevating him to the status of their father in the eyes of the text [רד״ק].