Not same sex, but the default in Spanish is to use the masculine form when a group includes a mix of male and female. So, my "niña" and my "niño" together are my "niños," or "hija"- daughter - and "hijo"- son- together are "hijos." This language sexism drives DD insane and she insists that I refer to her and DS as daughter and son separately, instead of using the masculine plural.