Does it ever become acceptable for a stepparent to treat their stepchildren as if they were their biological children? As one might expect, the answer is "it depends." If a stepparent is the only parent their kid has ever known and they call them "mom" or "dad," it's safe to assume that they can and should parent them as if they were their biological parents. If a child has lived with their stepparent since they could remember, but always regards them as a stepparent and has both of their biological parents in their life, it can be somewhat of a gray area. A kid might reluctantly accept discipline from a stepparent but feel resentful that they're taking on that role. It's far more common for stepparents to refrain from actual parenting if they enter a child's life when the child is eight or older. However, it always depends on the specific situation the family is in.