Cornelia was the daughter of Scribonia and her second husband. She was stepdaughter to Octavian through her mother's third marriage and half-sister to Julia the Elder, Augustus' only biological child.
Parentage
Cornelia is a shadowy figure; three primary sources comprise almost all of what we know of Cornelia's origins. First is a passage from Suetonius, who informs us that previous to her marriage to Octavian Scribonia was twice married, both times to ex-consuls, but only from one marriage did she have any children. Next is an inscription that attests to a slave owned by Scribonia and her son, Cornelius Marcellinus. Last is an elegy written by Sextus Propertius, a message addressed to Lucius Aemilius Lepidus Paullus from his dead wife, Cornelia. John Scheid has drawn from these three sources five definite facts about her:
Before marrying Caesar Octavian, Scribonia had two consular husbands, the second of which made her mother;
Scribonia had a son named Cornelius Marcellinus;
Scribonia had a daughter named Cornelia;
Cornelia died the year of her brother's consulate;
Scheid expands on the last point, noting that Cornelia must have died before her husband had in 13 BC, for Lepidus went on to marry Claudia Marcella, who in turn married Marcus Valerius Messalla Barbatusafter the death of her husband. Now the name of one of Scribonia's husbands has been agreed to since Bartolomeo Borghesi, based on the name of her known son, argued he was Gnaeus Cornelius Lentulus Marcellinus, consul in 56 BC. Since Propertius' poem alludes to her descent from Scipio Aemilianus, scholars attempted to identify the other husband with a possible descendant of Scipio Aemilianus, unaware that Lentulus Marcellinus could trace his ancestry to that man, while explaining away Suetonius' statement that Scribonia had children by only one man. As a result, various other consular Publii Cornelii have been identified as her first husband, such as the suffect consul of 38 BC, and the suffect consul of 35 BC. Thus none of the possible Cornelii could be her father. But if Suetonius is accepted at his word, the simplest solution is to accept that Cornelia is the daughter of the consul of 56. Scheid, who arrived at this conclusion, was able to then show that her brother Cornelius Marcellinus was Publius Cornelius Lentulus Marcellinus, consul of 18 BC. Syme, who argued in that her brother must be Publius Cornelius Scipio, suffect consul in 16 BC provided one more argument in favor of his position. He notes the elegy about her follows another poem that is clearly dated to 16 BC, and that the rest of the poems in his collection are arranged in chronological order. But with the evidence of the Fasti Tauromenitani, it would be easier to accept that the poem about Cornelia is misplaced than to fit a hypothetical Cornelius Scipio into a consular list that is complete for these years. Based on Scheid's arguments, we can conclude Cornelia was born between 50 and 40 BC, and further surmise that she was of child-bearing age around 30 BC. Since her brother Cornelius Marcellinus was consul for the entire year of 18 BC, that was the year of her death, years before her husband Lepidus. Regardless of the year of her death, we are told Augustus, her stepfather, grieved her death as he found her a worthy elder sister to his daughter, Julia.
Family
Cornelia was married only once, to the Lucius Aemilius Lepidus Paullus mentioned above, and who was censor in 22 BC. Their children were:
