Different children need different things and most parents attempt to meet their children's individual needs, whenever possible. Despite that, when it comes to estate planning, the first instinct of many parents is to divide the estate equally between the children. However, dividing an estate equally is not necessarily dividing it fairly in every case.
An estate plan that is fair to the children may be one that considers their different life circumstances. If one child is independently wealthy and another is not, due to a career in public service, it might fair to give the wealthy child less than the other in an estate plan. In some cases, this approach might not be fair, as it is possible that the wealthy child could fall on hard times.
Another important consideration is a number of assistance parents have already given to the children. If one child has received more from the parents than the other, then that can be rectified in an estate plan. It is important for parents to think about what is truly fair for their families. If the parents are going to do something their children might think is unfair, then let them know the reasons for it, instead of surprising them in a will.
Reference: Wills, Trusts & Estates Prof Blog (July 31, 2017) "Be Fair to Your Heirs: Treating Children Fairly in Your Will."