21. Germanicus was Claudius' brother. Who was his sister?
From Quiz Roman Emperor: Life and Reign of Claudius
Answer:
Livilla
Born in 13 BC, Livilla was the sole daughter of Drusus the Elder and Antonia Minor. She was also the paternal aunt of Caligula. She was named after Livia Drusilla, Augustus' wife.
Livilla's first husband was Augustus' grandson, Gaius Caesar, who died of a sudden illness in 4 AD. She later married Tiberius' son, Drusus the Younger. They had three children.
Tacitus states that although Livilla was a very beautiful woman, she was jealous and resentful of Agrippina the Elder due to the unfavorable comparisons regularly made between the two of them.
Livilla had an affair with Sejanus, the close friend and confidant of Tiberius, who later had him executed. Rumours abounded that Sejanus was the biological father of Livilla and Drusus the Younger's twins. Suetonius, Tacitus, and Cassius Dio all agree the Sejanus had Drusus the Younger poisoned, and possibly had Livilla's help. This was supported by Sejanus' wife's suicide note, which claimed that both her husband and Livilla had poisoned Drusus the Younger.
It it not known exactly how Livilla died, but she died around 31 AD. According to several sources, Tiberius handed her over to her mother, Antonia Minor. Her mother then locked Livilla in a room to starve to death, as she wanted to avoid public embarrassment for her family.