Question: Who is Gaius Rubellius Blandus's father-in-law?

Barthold A. Butenschøn Sr.
Hans Barthold Andresen Butenschøn( 27 December 1877 – 28 November 1971) was a Norwegian businessperson.
He was born in Kristiania as a son of Nils August Andresen Butenschøn and Hanna Butenschøn, and grandson of Nicolay Andresen.
Together with Mabel Anette Plahte( 1877 – 1973, a daughter of Frithjof M. Plahte) he had the son Hans Barthold Andresen Butenschøn Jr. and was through him the father- in- law of Ragnhild Butenschøn and grandfather of Peter Butenschøn.
Through his daughter Marie Claudine he was the father- in- law of Joakim Lehmkuhl, through his daughter Mabel Anette he was the father- in- law of Harald Astrup( a son of Sigurd Astrup) and through his daughter Nini Augusta he was the father- in- law of Ernst Torp.
He took commerce school and agricultural school.
He was hired in the family company N. A. Andresen& Co, and became a co-owner in 1910.
He eventually became chief executive officer.
The bank changed its name to Andresens Bank in 1913 and merged with Bergens Kreditbank in 1920.
The merger was dissolved later in the 1920s.
He was also a landowner, owning Nedre Skøyen farm and a lot of land in Enebakk.
He chaired the board of Nydalens Compagnie from 1926, having not been a board member before that.
He also chaired the supervisory council of Forsikringsselskapet Viking and Nedre Glommen salgsforening, and was a supervisory council member of Filharmonisk Selskap.
He was a member of the gentlemen's club SK Fram since 1890, and was proclaimed a lifetime member in 1964.
He was buried in Enebakk.
James Armour (Master mason)
James Armour (15 January 1730 – 20 September 1798) was a master mason and father of Jean Armour, and therefore the father-in-law of the poet Robert Burns.
Peter Burroughs
Peter Burroughs( born 27 January 1947) is a British television and film actor, the director of Willow Management.
He is the father- in- law of actor and TV presenter Warwick Davis.
Gaius Rubellius Blandus
Gaius Rubellius Blandus was a Roman senator who lived during the Principate.
Blandus was the grandson of Rubellius Blandus of Tibur, a member of the Equestrian class, who was the first Roman to teach rhetoric.
He was suffect consul from August to December AD 18 with Marcus Vipstanus Gallus as his colleague.
In AD 33, he married Julia Livia, granddaughter of the Roman emperor Tiberius.
Ogawa Mataji
Viscount was a general in the early Imperial Japanese Army.
He was also the father- in- law of Field Marshal Gen Sugiyama.
Ludwig von Westphalen
Johann Ludwig von Westphalen( 11 July 1770 – 3 March 1842) was a liberal Prussian civil servant and the father- in- law of Karl Marx.
John Adams (merchant)
John Adams( 1672 or 1673 – 1745) was an American- born Canadian merchant and member of the Nova Scotia Council.
He was the father- in- law of Henry Newton( politician).
Julia Livia
Julia Livia (c.7–43 AD), sometimes referred to as Julia Drusi Caesaris filia (Julia, daughter of Drusus Caesar), was the daughter of Drusus Julius Caesar and Livilla, and granddaughter of the Roman Emperor Tiberius.
She was also a first cousin of the emperor Caligula, and niece of the emperor Claudius.
Rubellius Blandus
Rubellius Blandus was a Roman, native of Tibur( Tivoli, Italy).
He was the first Equestrian of Ancient Rome to teach rhetoric and thus made it more respectable( Sen., Controv. 2, 5).
He was the teacher of Papirius Fabianus, who was in turn the teacher of Seneca the Younger.
His grandson Gaius Rubellius Blandus was a suffect consul of 18.
Rubellia Bassa
Rubellia Bassa( born between 33- 38) was a daughter of Gaius Rubellius Blandus, consul in AD 18 and possibly his wife Julia Livia( killed 43) or an earlier wife.

Answer: Drusus Julius Caesar