Any person over the age of 14 years can be a witness to a will. However, if the testator wants to leave any assets to a person under a will, that person should not be a witness to his will. Doing so will invalidate the inheritance to that particular person. This precaution is also applicable to contingent beneficiaries. For example, the testator wants to “give the car to Adam; but if Adam does not survive me, give the car to Bob; if Bob does not survive me, give the car to Carl”. In this case, not only Adam should not be a witness, Bob and Carl should also refrain from being witnesses because you never know whether the car will eventually go to Bob or Carl.