divorced or widowed men and women marry again and live with children from their previous, or earlier, marriages. Some kids have stepparents - that is, mothers or fathers related to them by marriage instead of biology. In other families, some youngsters under the age of 18 have to take care of kids - either their own or their younger siblings. In different countries around the world, there are also same-sex partnership - with or without childless - marriages, unmarried live-in relationships, communal living groups, and so on.