Question: Who is Marcus Aemilius Lepidus (Executed 39)'s father-in-law?

Knowledge 1: Marcus Aemilius Lepidus (executed 39)
Marcus Aemilius Lepidus, (6–39) was the son of consul Lucius Aemilius Paullus.He and his sister Aemilia Lepida were both married to siblings of the Emperor Caligula (Aemilia married Caligula's elder brother Drusus Caesar; Lepidus married to Caligula's younger sister Julia Drusilla).He was also great-grandson of Lucius Aemilius Lepidus Paullus (consul of 50 BC and brother of the triumvir Marcus Aemilius Lepidus).Some areas of his lineage are unclear.However, through his mother Julia the Younger, Lepidus was the great grandson of Emperor Augustus Caesar.Lepidus married Caligula's sister Drusilla sometime in November or December of 37.Little is known about him prior to this.Drusilla had been married to Lucius Cassius Longinus since 33 but Caligula forced his brother-in-law to divorce Drusilla so that she could marry Lepidus.The marriage lasted until Drusilla's death in June 38.They had no children.Because of this marriage, Lepidus had become a close friend to Caligula and his family.After the death of Gemellus in 37, Lepidus was publicly marked by Caligula as his heir.In late 38, when the governor of Egypt Aulus Avilius Flaccus was arrested, Lepidus successfully persuaded Caligula to exile Flaccus to Andros rather than Gyarus.Sometime in 39, however, Caligula made public letters by his sisters Agrippina the Younger and Julia Livilla that detailed an adulterous affair with Lepidus and a plot against the emperor.Lepidus was executed and Caligula's sisters were exiled.Agrippina was given the bones of Lepidus in an urn, and she carried them to Rome.Caligula sent three daggers to the Temple of Mars the Avenger to celebrate the death.In the Senate, Vespasian made a motion that the remains of Lepidus be thrown away instead of buried.The motion was carried and Lepidus was not given a proper burial. [SEP] Knowledge 2: Julia Drusilla
Julia Drusilla (Classical Latin:) (16 September AD 16 – 10 June AD 38) was a member of the Roman imperial family, the second daughter and fifth child of Germanicus and Agrippina the Elder to survive infancy.She had two sisters, Julia Livilla and the Empress Agrippina the Younger, and three brothers, Emperor Caligula, Nero Julius Caesar, and Drusus.She was a great-granddaughter of the Emperor Augustus, grand-niece of the Emperor Tiberius, niece of the Emperor Claudius, and aunt of the Emperor Nero.
Knowledge 1: Julia Drusilla
Julia Drusilla (Classical Latin:) (16 September AD 16 – 10 June AD 38) was a member of the Roman imperial family, the second daughter and fifth child of Germanicus and Agrippina the Elder to survive infancy.She had two sisters, Julia Livilla and the Empress Agrippina the Younger, and three brothers, Emperor Caligula, Nero Julius Caesar, and Drusus.She was a great-granddaughter of the Emperor Augustus, grand-niece of the Emperor Tiberius, niece of the Emperor Claudius, and aunt of the Emperor Nero. [SEP] Knowledge 2: Junia Secunda
Junia, called Junia Secunda by modern historians to distinguish her from her sisters, was an ancient Roman woman who lived in the 1st century BC.She was married to the triumvir Marcus Aemilius Lepidus.
Knowledge 1: Marcus Aemilius Lepidus (executed 39)
Marcus Aemilius Lepidus, (6–39) was the son of consul Lucius Aemilius Paullus.He and his sister Aemilia Lepida were both married to siblings of the Emperor Caligula (Aemilia married Caligula's elder brother Drusus Caesar; Lepidus married to Caligula's younger sister Julia Drusilla).He was also great-grandson of Lucius Aemilius Lepidus Paullus (consul of 50 BC and brother of the triumvir Marcus Aemilius Lepidus).Some areas of his lineage are unclear.However, through his mother Julia the Younger, Lepidus was the great grandson of Emperor Augustus Caesar.Lepidus married Caligula's sister Drusilla sometime in November or December of 37.Little is known about him prior to this.Drusilla had been married to Lucius Cassius Longinus since 33 but Caligula forced his brother-in-law to divorce Drusilla so that she could marry Lepidus.The marriage lasted until Drusilla's death in June 38.They had no children.Because of this marriage, Lepidus had become a close friend to Caligula and his family.After the death of Gemellus in 37, Lepidus was publicly marked by Caligula as his heir.In late 38, when the governor of Egypt Aulus Avilius Flaccus was arrested, Lepidus successfully persuaded Caligula to exile Flaccus to Andros rather than Gyarus.Sometime in 39, however, Caligula made public letters by his sisters Agrippina the Younger and Julia Livilla that detailed an adulterous affair with Lepidus and a plot against the emperor.Lepidus was executed and Caligula's sisters were exiled.Agrippina was given the bones of Lepidus in an urn, and she carried them to Rome.Caligula sent three daggers to the Temple of Mars the Avenger to celebrate the death.In the Senate, Vespasian made a motion that the remains of Lepidus be thrown away instead of buried.The motion was carried and Lepidus was not given a proper burial. [SEP] Knowledge 2: Junia Secunda
Junia, called Junia Secunda by modern historians to distinguish her from her sisters, was an ancient Roman woman who lived in the 1st century BC.She was married to the triumvir Marcus Aemilius Lepidus.

Answer: Germanicus