Where a future estate shall be limited to heirs, or issue, or children, posthumous children shall be entitled to take in the same manner as if living at the death of their parent; and a future estate depending on the contingency of the death of any person without heirs, or issue, or children shall be defeated by the birth of a posthumous child of such person.
D.C. Code § 42-704
Personal property, applicable laws, see § 42-523. .