Imperial Rome's first decades. Note that descendancy of the Julii Caesares before the generation of Julius Caesar's grandfather is in part conjectural, but as presented by scholars.[1]
Claudii up to Augustus' generation. The next generation had both Claudii with a Julia as ancestor, as Claudii adopted into the Julii Caesares family. After Tiberius
, the remaining three emperors of the dynasty had, outside adoptions, ancestors in both the Julian and the Claudian families.
Generation of Julius Caesar's grandfather
Gaius Julius Caesar II and Lucius Julius Caesar II may have had
Sextus Julius Caesar, the military tribune of 181 BC, as a common ancestor.[1]
Generation of Julius Caesar's grandfather
Popilii Laenates
Gaius Julius Caesar
Marcia
Lucius Julius Caesar
Popillia
Gaius Julius Caesar Strabo Vopiscus
Julia
Generation of Julius Caesar's father
This generation of Julii Caesares has two
Gaius Julius Caesar (proconsul of Asia), married to a consul's daughter, and Lucius Julius Caesar proved to be quintessential ancestors of those who held Imperial power in the Julio-Claudian dynasty.[1]
By this time marriages with a political agenda among the powerful families were in full swing, however not yet between Julii Caesares and Claudii.
Julius Caesar's second wife Pompeia, possibly a great-granddaughter of Lucius Julius Caesar II, was a granddaughter of Sulla. His third wife Calpurnia is said to be younger than his daughter. His son Caesarion resulted from his relation with Cleopatra.[1]
Claudii were a powerful gens with consuls and other high ranking politicians in several of its families across several generations. In this generation the first marriages between Claudii and descendants of the Julii Caesares
took place. This however didn't mean yet that the dynastic family trees of both gentes got merged into a single one: that didn't happen until the adoption of Claudii by (adopted) Julii Caesares in the generations to come.
Octavian, who by then was adopted in the Julii Caesares family by the testament of his uncle Julius Caesar. After her first husband's death, Octavia married Mark Antony, who besides the offspring of his first three marriages had had children by Cleopatra
Claudius. Their son Tiberius, by birth a Claudius, was later adopted by Augustus, thus, like his stepfather Augustus, becoming one of the Julii Caesares
by adoption: from this moment this first dynasty of Roman emperors was both Julian and Claudian. The further emperors of this dynasty had both Julian and Claudian ancestors.