A more thorough explanation:

Definition: House law is a set of rules created by the head of a royal or noble family, or a prominent private family, that governs how family members interact with each other and how they handle important events like marriage, property ownership, and inheritance. These rules are not legally binding, but they are enforced within the family through personal and economic consequences.

• A royal family might have a house law that dictates who can marry whom within the family, in order to maintain bloodlines and alliances.
• A wealthy family might have a house law that requires all family members to contribute a certain amount of money to a family trust each year, in order to ensure financial stability for future generations.
• A noble family might have a house law that determines how property is divided among heirs, in order to prevent disputes and maintain family unity.

These examples illustrate how house law can be used to regulate family relationships and ensure that the family's interests are protected. While these rules are not legally binding, they are often taken very seriously within the family and can have significant consequences for those who violate them.