A stepfather or stepdad is the husband of one's biological mother, and not one's biological father.
He is not one's biological father. A stepfather or stepdad is the man who married one's biological mother.
A stepfather or stepdad is the man who married one's biological mother. He is not one's biological father.
A stepfather or stepdad is the man who married one's biological mother. He is not one's biological father.