I went to school in the 1970s, and it was a small town, but I knew no one who had a stepparent. Only 2 boys were from single-parent families; for one, the father had died, and for the other, he had just gone.
I think it's good these days that it does not matter what families they come from though I know it can get messy in some circumstances. i was just really interested, as I really did not know until I was an adult about stepparents, etc.