In estate planning, “equal” isn’t necessarily the same as “fair.” Sometimes, parents’ wills give different amounts to the kids, for very good reasons. The key is that everyone in the family knows about the division ahead of time.

Still, I rarely see an estate plan that does not treat children equally. When I do see inequality, the justification is usually that a parent is estranged from one child and leaves him or her nothing.

Many experts on the psychology of estate planning recommend that parents divide their estates equally among children. The main reason is to help enhance sibling relationships after the parents’ deaths. The goal is to eliminate the potential for hurt feelings and perceived injustice if parents…