Have I lost my rights to my grandfather’s estate as an heir because I was adopted?

Adoption cuts off the right of inheritance by and through the natural/biological parents. The adoptee instead inherits from his new adopted family, including adopting parents and grandparents unless someone makes a will and specifically disinherits the adopted child. Where did your biological grandfather live at the time of his death? When did he die? Did he have a will? If he made a valid will and voluntarily chose to include you, then you could still inherit because you are a named beneficiary. If he had no will, then his children (assuming he had no surviving spouse) would inherit. If he had a will leaving his property to his children they would also inherit. In either case, if one or more of those children predeceased him, then the share of the deceased child would pass to the children of the deceased child. Because you were adopted out, that means that you are no longer a child of your biological parent. Instead, your biological parent's share would pass to any siblings of yours who were not adopted or if there is no siblings, then to any other surviving children of your grandfather. If your grandfather did not live in North Carolina at the time of his death, I suggest that you confirm with an adoption or probate attorney to find out the laws in the state where your grandfather resided.