Question: Who is Titus Tarquinius's paternal grandfather?
Answer: Lucius Tarquinius Priscus

Ancient accounts of the regal period mingle history and legend. Tarquin was said to have been the son or grandson of Lucius Tarquinius Priscus, the fifth king of Rome, and to have gained the throne through the murders of both his wife and his elder brother, followed by the assassination of his predecessor, Servius Tullius. His reign is described as a tyranny that justified the abolition of the monarchy