The bond between a parent and a child doesn't necessarily come from biology -- there are plenty of stepparents who feel just as strongly connected to a stepchild as they could any biological child of their own.
Unfortunately, if those feelings aren't given legal standing through the adoption process, your stepchild has no real rights when the end of your life comes.
That means that your legal next-of-kin could forcibly exclude your stepchild from a number of important things:
—The ability to have a say about what medical care you receive if you aren't able to speak for yourself
—The ability to have a say about your nursing care if you need to be placed in a nursing home
—The ability to visit you, if you are in a nursing home
—Decisions about the way that your funeral is handled, including whether you are buried or cremated and where your remains are kept
—Inheritance rights under intestacy laws, if you die and you don't leave a will, or the will you do leave is invalidated for some reason
—Inclusion in any language in your will or estate that refers to "all" of you children or heirs
—The ability to sue on your behalf for a wrongful death claim if your death was caused by someone's negligence
While you can always hope that any biological children you have or (if you don't have biological children) your other close relatives will adhere to your wishes and treat your stepchild as if he or she were your own, the truth is that you never really know how people will behave once you aren't able to exert any control over the situation. You have no way of knowing if some close relative resents your stepchild or thinks of him or her as simply an outsider and not a "real" member of the family.
During your stepchild's minor years, it may have been cost-prohibitive to do an adoption. Or, there may have been legal tangles involved when it came to severing the parental rights of your stepchild's biological mother or father. Adopting an adult, however, is much simpler and easier to do because your stepchild can simply consent to the process.
Adopting your adult stepchild is not only a reasonable thing to do, it's the best way to protect his or her rights -- and yours -- as you head into the last few years of your life.
Source: FindLaw, "Nebraska Adoption Laws," accessed Jan. 09, 2017