A parent-in-law is a person who has a legal affinity with another by being the parent of the other's spouse. Many cultures and legal systems impose duties and responsibilities on persons connected by this relationship. A person is a son-in-law or daughter-in-law to the parents of the spouse, who are in turn also the parents of those sisters-in-law and brothers-in-law if any who are siblings of the spouse as opposed to spouses of siblings. Together the members of this family affinity group are called the in-laws. A father-in-law is the father of a person's spouse. A mother-in-law is the mother of a person's spouse.