Question: are the targaryens and baratheons related?
Answer: The Baratheons we see in Game of Thrones; Robert, Stannis and Renly are not just related to the Targaryens through Orys though. The three Baratheon brothers are actually 1/4 Targaryen as there grandmother was Rhaelle Targaryen daughter of Aegon V. This would actually make Robert Baratheon and Daenerys second cousins.