There is no requirement that the relatives of a testator (i.e. the maker of a Will) must inherit. Even children do not have automatic rights of inheritance. As long as the Will conforms with the mandated state requirments for valid execution, it is legal. So if the testator was of age and mental capacity, it was signed by the testator, the proper number of witnesses were present and attested to its execution, etc. it will hold up to any challenge by family members.