Ind. Code § 29-1-2-8
For all purposes of intestate succession, including succession by, through, or from a person, both lineal and collateral, an adopted child shall be treated as a natural child of the child's adopting parents, and the child shall cease to be treated as a child of the natural parents and of any previous adopting parents. However, if a natural parent of a child born in or out of wedlock marries the adopting parent, the adopted child shall inherit from the child's natural parent as though the child had not been adopted, and from the child's adoptive parent as though the child were the natural child. In addition, if a person who is related to a child within the sixth degree adopts such child, such child shall upon the occasion of each death in the child's family have the right of inheritance through the child's natural parents or adopting parents, whichever is greater in value in each case.
IC 29-1-2-8