When Rhyhorn, Nidoqueen and their babies are introduced, we can see that their babies are Rhyhorn babies and Nidoqueen babies. In the Pokémon World it is not important the category of fathers of babies because mothers provides theirs. Because of this, and assuming that the Rhyhorn present in the scene is male since Nidoqueen can only be female, all babies born from that Nidoqueen's eggs should have been either female Nidoran or male Nidoran.