Secundus was descended from a respectable, if undistinguished
plebeian family. His father and grandfather were also named
Quintus, and from their shared
filiation we know that Secundus was the brother of
Gaius Poppaeus Sabinus, consul
ordinarius in the same year that Secundus was
suffectus. It is unclear which was the elder; typically an elder son would be named after his father, but the cognomen
Secundus suggests that he was the younger brother. ==Consulship==