Families are formed at the turn of the year from persons living in the same dwelling according to the population information system of the Population Register Centre. The statistics comprise families and families with children, and their demographic data. Families are classified into families without children, married or cohabiting couples living with children, and single-parent families. Cohabiting couples are deduced from living together. The statistics contain data on the age, language, nationality and country of birth of spouses/parents, and on the age and gender of each child living at home. Families with children are those that include children under the age of 18.