There is a widely held expectation, which has existed for most of recorded history and in most cultures, that a wife is not to have sexual relations with anyone other than her legal husband. A breach of this expectation of fidelity is commonly referred to as adultery or extramarital sex. Historically, adultery has been considered to be a serious offense, sometimes a crime, and a sin. Even if that is not so, it may still have legal consequences, particularly as a ground for a divorce. Adultery may be a factor to consider in a property settlement, it may affect the status of children, the custody of children; moreover, adultery can result in social ostracism in some parts of the world. In addition, affinity rules of Catholicism, of Judaism and of Islam prohibit an ex-wife or widow from engaging in sexual relations with and from marrying a number of relatives of the former husband.