What is the ruling regarding the inheritance of newborn twins where only one exhibits the signs of life (istihlal), and the identity of the living one is unknown?
Chapter on Distant Kindred (Dhawu al-Arham)
Al-Mughni
Book of Inheritance Shares (Farā'id)
Primary text
If the twins are both males, both females, or one male and one female where their inheritance shares are equal, there is no difference in their inheritance distribution, and thus no issue arises. If the twins are a male and a female whose inheritance shares differ, one opinion, attributed to the Qadi among our scholars, states that a casting of lots (qur'a) is performed between them. The one drawn by lot is deemed the one who cried out (mustahil). This is analogous to the case where a man divorces one of his unknown wives by a specific designation and then dies before ascertaining which one; lots are cast to determine the specific wife. The evidence cited for differentiating cases where inheritance differs is the analogy to the undetermined divorced wife.
Supporting text
Al-Khabari stated that there is no explicit ruling (nass) from the Salaf (early generations) concerning this matter. The school of Fardiyyun (mathematicians/heirs specialists) mandates working the problem under both scenarios (male was the one crying out, or female was the one crying out). Each heir is then given the certain portion (al-yaqin) derived from both scenarios, and the remainder is suspended until the heirs reach a settlement. Another possible resolution is that the suspended portion is divided between them based on the probability of each scenario occurring.