Adults may be adopted with consent of the person to be adopted.Most Relevant Indiana Statute:
§ 31-19-2-1 31-19-2-1. Adoption of adult; petition; venue; consent; investigationSec. 1.
(a) An individual who is at least eighteen (18) years of age may be adopted by a resident of Indiana:
(1) upon proper petition to the court having jurisdiction in probate matters in the county of residence of the individual or the petitioner for adoption; and
(2) with the consent of the individual acknowledged in open court.
(b) If the court in which a petition for adoption is filed under this section considers it necessary, the court may order:
(1) the type of investigation that is conducted in an adoption of a child who is less than eighteen (18) years of age; or
(2) any other inquiry that the court considers advisable;before granting the petition for adoption.