Final answer:
The family in question, which includes a mother, stepfather, and two stepbrothers, constitutes a blended family, a term that describes families formed by merging individuals from previous relationships.
Step-by-step explanation:
The family structure described in the student's question is that of a blended family. A blended family is one in which adults with children from previous relationships marry or cohabit, bringing together multiple family units. Since the family in question includes a mother, stepfather, and two stepbrothers, it is indicative of a household where family members have united from different origins. This is becoming more common in societies where divorce and remarriage are prevalent, resulting in a family dynamic that includes stepparents and stepchildren.
In the United States, blended families make up a significant portion of household arrangements and have been steadily represented since the 1980s. Changes in societal norms have led to various family types becoming more recognized, including single-parent families, extended families, and nuclear families, which refer to a household with two married parents and their children. The notion of a traditional nuclear family has evolved with the acceptance of cohabiting parents, single and same-sex parents, and other variations that challenge traditional paradigms.