Final answer:
Approximately 10 percent of all children are living in a married stepfamily with one biological parent and one stepparent, and this is more common among younger children than older ones.
Step-by-step explanation:
About 10 percent of all children (5.3 million) are living in a married stepfamily with one biological parent and one stepparent. Among children living in two-parent households, 9 percent live with a biological or adoptive parent and a stepparent. Stepparents are an additional family element in two-parent homes, with the majority of these children living with their biological mother and a stepfather. Family structure has indeed varied with the age of the child, with older children being less likely to live with two parents compared to younger ones, and they are also more likely to live with stepparents.