The limitation(s) on who can create a will can really be boiled down to one overarching limitation: capacity. As long as the testator is recognized to be capable of understanding (1)the nature and extent of his/her property, (2) the effect of the disposition they are making, (3) the nature of their relationships with apparent heirs, and how the above three criterion work together to dispose of their property, they generally are able to act as testator to a will. Commonly it is understood that there are two main groups of people who cannot create a will. The first is minors, and second is the elderly who are believed to not be “of sound mind.”
The requirement that the testator reach the age of majority arises under the presumption that a minor does not have the capacity to adequately understand the nature and extent of his/her potential property simply because he or she is a minor. The second is another reflection on a concern for the capacity of the testator. The need that the testator be of sound mind can apply to any age of a potential testator, but often arises in cases dealing with elderly testators whose heirs or heirs apparent want to contest the terms of a will arguing that mom, dad, grandma, or grandpa did not understand what they were doing.
If you are worried about someone contesting the capacity of a testator to a will, you can seek a medical examination (ideally from a doctor who has previous interaction with the testator) to provide a written statement regarding the testator’s capacity that can be used as evidence to defend a potential challenge.
Image by: Ken Mayer