Final answer:
The answer is false. A nuclear family consists of two parents and their children, while an extended family includes other relatives such as grandparents. Modern variations of the nuclear family can differ from traditional structures.
Step-by-step explanation:
The statement that nuclear families typically comprise the grandparents, parents, and their children who are all living under the same roof is false. A nuclear family usually consists of two parents (traditionally a married husband and wife) and their children living in the same household. This structure is often seen as the nucleus, or core, of the family unit. Meanwhile, an extended family includes a larger group of relatives such as grandparents, aunts, uncles, cousins, and sometimes even more distant relatives, often living together or maintaining close relationships.
Modern variations of the nuclear family include single-parent households, same-sex couples with children, and households with parents who are not married but cohabiting. Based on the 2010 U.S. Census, 66 percent of children under seventeen years old live in a household with two married parents, which is lower than it was in previous decades. Some children also live with two cohabiting parents or in single-parent households.