Examples of circumstances giving rise to a natural obligation are: (1) When a civil obligation has been extinguished by prescription or discharged in bankruptcy. (2) When an obligation has been incurred by a person who, although endowed with discernment, lacks legal capacity. (3) When the universal successors are not bound by a civil obligation to execute the donations and other dispositions made by a deceased person that are null for want of form. La. C.C. § 1762 Acts 1984, No. 331, §1, eff. Jan