You can disclaim your interest in your mother's estate, but then you would be treated as having predeceased your mother and then your share would pass under the provisions of the will. You would not have a say in who got your share.
Alternatively, you could take your share of the inheritance and then gift it to whomever you like. You may have to file a gift tax return, but you probably won't owe a gift tax.
Answered on Jan 13th, 2016 at 2:57 PM